diff --git a/modules/backend/ServiceProvider.php b/modules/backend/ServiceProvider.php
index a2b61abb9e..9ff5e505ad 100644
--- a/modules/backend/ServiceProvider.php
+++ b/modules/backend/ServiceProvider.php
@@ -97,6 +97,7 @@ protected function registerAssetBundles()
             $combiner->registerBundle('~/modules/backend/widgets/reportcontainer/assets/less/reportcontainer.less');
             $combiner->registerBundle('~/modules/backend/widgets/table/assets/less/table.less');
             $combiner->registerBundle('~/modules/backend/formwidgets/repeater/assets/less/repeater.less');
+            $combiner->registerBundle('~/modules/backend/formwidgets/fieldset/assets/less/fieldset.less');
             $combiner->registerBundle('~/modules/backend/formwidgets/fileupload/assets/less/fileupload.less');
             $combiner->registerBundle('~/modules/backend/formwidgets/nestedform/assets/less/nestedform.less');
             $combiner->registerBundle('~/modules/backend/formwidgets/richeditor/assets/js/build-plugins.js');
@@ -258,6 +259,7 @@ protected function registerBackendWidgets()
             $manager->registerFormWidget(\Backend\FormWidgets\ColorPicker::class, 'colorpicker');
             $manager->registerFormWidget(\Backend\FormWidgets\DataTable::class, 'datatable');
             $manager->registerFormWidget(\Backend\FormWidgets\DatePicker::class, 'datepicker');
+            $manager->registerFormWidget(\Backend\FormWidgets\FieldSet::class, 'fieldset');
             $manager->registerFormWidget(\Backend\FormWidgets\FileUpload::class, 'fileupload');
             $manager->registerFormWidget(\Backend\FormWidgets\IconPicker::class, 'iconpicker');
             $manager->registerFormWidget(\Backend\FormWidgets\MarkdownEditor::class, 'markdown');
diff --git a/modules/backend/formwidgets/FieldSet.php b/modules/backend/formwidgets/FieldSet.php
new file mode 100644
index 0000000000..70da8e0736
--- /dev/null
+++ b/modules/backend/formwidgets/FieldSet.php
@@ -0,0 +1,102 @@
+<?php
+
+namespace Backend\FormWidgets;
+
+use Backend\Classes\FormField;
+use Backend\Classes\FormWidgetBase;
+use Backend\Widgets\Form;
+
+/**
+ * FieldSet
+ * Renders a fieldset from multiple form fields.
+ *
+ * @package winter\wn-backend-module
+ * @author Marc Jauvin <marc.jauvin@gmail.com>
+ */
+class FieldSet extends FormWidgetBase
+{
+    /**
+     * @inheritDoc
+     */
+    protected $defaultAlias = 'fieldset';
+
+    /**
+     * @var array Field configuration
+     */
+    public $fields;
+
+    /**
+     * @var bool Determines if this form field should display comments and labels.
+     */
+    public $showLabels = false;
+
+    /**
+     * @var Form form widget reference
+     */
+    protected $formWidget;
+
+    /**
+     * @inheritDoc
+     */
+    public function init()
+    {
+        $this->fillFromConfig([
+            'fields',
+        ]);
+
+        if ($this->formField->disabled) {
+            $this->previewMode = true;
+        }
+
+        $config = $this->makeConfig(['fields' => $this->fields]);
+        $config->model = $this->model;
+        $config->data = $this->getLoadValue();
+        $config->alias = $this->alias . $this->defaultAlias;
+        // set arrayName from parent form to save fields to the model
+        $config->arrayName = $this->getParentForm()->arrayName;
+        $config->isNested = true;
+
+        $widget = $this->formWidget = $this->makeWidget(Form::class, $config);
+        $widget->previewMode = $this->previewMode;
+        $widget->bindToController();
+    }
+
+    protected function loadAssets()
+    {
+        $this->addCss('css/fieldset.css', 'core');
+    }
+
+    /**
+     * Returns the save data for the nested fields, to be merged into the parent
+     * form's data as if these fields were defined at that level. Reusing the nested
+     * form's getSaveData() ensures number casting, widget getSaveValue() handling,
+     * NO_SAVE_DATA exclusion and disabled/hidden skipping all behave identically to
+     * a regular field.
+     */
+    public function getSaveData(): array
+    {
+        return $this->formWidget->getSaveData();
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function render()
+    {
+        $this->prepareVars();
+        return $this->makePartial('fieldset');
+    }
+
+    public function prepareVars()
+    {
+        $this->formWidget->previewMode = $this->previewMode;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function getSaveValue($value)
+    {
+        return FormField::NO_SAVE_DATA;
+    }
+}
diff --git a/modules/backend/formwidgets/fieldset/assets/css/fieldset.css b/modules/backend/formwidgets/fieldset/assets/css/fieldset.css
new file mode 100644
index 0000000000..933d9b103f
--- /dev/null
+++ b/modules/backend/formwidgets/fieldset/assets/css/fieldset.css
@@ -0,0 +1,6 @@
+.fieldset{position:relative;min-height:30px;border:1px solid #d1d6d9;border-radius:0.5rem;box-shadow:inset 0 1px 0 rgba(209,214,217,0.25),0 1px 0 rgba(255,255,255,.5);margin-top:5px;padding:1em 1.25em 0 1.25em;background:#f5f5f5}
+.fieldset>legend{border:none;margin:0;padding-inline:1rem;width:fit-content;font-size:18px;color:inherit}
+.fieldset .control-tabs.primary-tabs .nav-tabs{margin:0}
+.fieldset .control-tabs.primary-tabs .nav-tabs>li.active>a:before{background-color:#f5f5f5;border-color:#f5f5f5}
+.fieldset .control-tabs.primary-tabs .nav-tabs>li>a>span.title:before,
+.fieldset .control-tabs.primary-tabs .nav-tabs>li>a>span.title:after{background-color:#f5f5f5}
diff --git a/modules/backend/formwidgets/fieldset/assets/less/fieldset.less b/modules/backend/formwidgets/fieldset/assets/less/fieldset.less
new file mode 100644
index 0000000000..3ae5a9e261
--- /dev/null
+++ b/modules/backend/formwidgets/fieldset/assets/less/fieldset.less
@@ -0,0 +1,41 @@
+@import "../../../../assets/less/core/boot.less";
+
+@panel-bg: #f5f5f5;
+
+.fieldset {
+    position: relative;
+    min-height: 30px;
+
+    border: 1px solid @input-border;
+    border-radius: 0.5rem;
+    box-shadow: @input-box-shadow;
+
+    margin-top: 5px;
+    padding: 1em 1.25em 0 1.25em;
+
+    background: @panel-bg;
+
+    & > legend {
+        border: none;
+        margin: 0;
+        padding-inline: 1rem;
+        width: fit-content;
+        font-size: 18px;
+        color: inherit;
+    }
+    .control-tabs.primary-tabs {
+        .nav-tabs {
+            margin: 0;
+            > li.active > a:before {
+                background-color: @panel-bg;
+                border-color: @panel-bg;
+            }
+
+            > li > a > span.title {
+                &:before, &:after {
+                    background-color: @panel-bg;
+                }
+            }
+        }
+    }
+}
diff --git a/modules/backend/formwidgets/fieldset/partials/_fieldset.php b/modules/backend/formwidgets/fieldset/partials/_fieldset.php
new file mode 100644
index 0000000000..6da5db39db
--- /dev/null
+++ b/modules/backend/formwidgets/fieldset/partials/_fieldset.php
@@ -0,0 +1,9 @@
+<?php $label = object_get($this->config, 'label'); ?>
+
+<fieldset class="fieldset">
+    <?php if ($label): ?>
+        <legend><?= e(trans($label)) ?></legend>
+    <?php endif ?>
+
+    <?= $this->formWidget->render(['section' => 'outside']) ?>
+</fieldset>
diff --git a/modules/backend/tests/widgets/FormFieldSetSaveTest.php b/modules/backend/tests/widgets/FormFieldSetSaveTest.php
new file mode 100644
index 0000000000..988cba7f62
--- /dev/null
+++ b/modules/backend/tests/widgets/FormFieldSetSaveTest.php
@@ -0,0 +1,196 @@
+<?php
+
+namespace Backend\Tests\Widgets
+{
+    use Backend\Classes\Controller;
+    use Backend\Classes\FormField;
+    use Backend\Classes\FormWidgetBase;
+    use Backend\Classes\WidgetManager;
+    use Backend\FormWidgets\FieldSet;
+    use System\Tests\Bootstrap\PluginTestCase;
+    use Winter\Storm\Database\Model;
+    use Backend\Widgets\Form;
+
+    class FormFieldSetSaveTestModel extends Model
+    {
+    }
+
+    /**
+     * A trivial form widget whose getSaveValue() observably transforms the posted value,
+     * used to prove that a fieldset's nested `widget` fields have getSaveValue() applied.
+     */
+    class FieldSetSaveStubWidget extends FormWidgetBase
+    {
+        protected $defaultAlias = 'fieldsetsavestub';
+
+        public function getSaveValue($value)
+        {
+            return is_string($value) ? strtoupper($value) : $value;
+        }
+    }
+
+    /**
+     * A nested form widget that opts out of saving (as e.g. FileUpload does, since its
+     * relation manages persistence). Its NO_SAVE_DATA sentinel must never reach the model.
+     */
+    class FieldSetNoSaveStubWidget extends FormWidgetBase
+    {
+        protected $defaultAlias = 'fieldsetnosavestub';
+
+        public function getSaveValue($value)
+        {
+            return FormField::NO_SAVE_DATA;
+        }
+    }
+
+    /**
+     * Covers Form::getSaveData()'s handling of the `fieldset` form widget: the fieldset
+     * visually groups fields but they must be saved as if they were regular fields at the
+     * parent level, while the fieldset container itself saves nothing.
+     */
+    class FormFieldSetSaveTest extends PluginTestCase
+    {
+        public function setUp(): void
+        {
+            parent::setUp();
+
+            // The backend module's form widgets are not auto-registered under PluginTestCase,
+            // so make the aliases used by the form field configs below resolvable.
+            WidgetManager::instance()->registerFormWidget(FieldSet::class, 'fieldset');
+            WidgetManager::instance()->registerFormWidget(FieldSetSaveStubWidget::class, 'fieldsetsavestub');
+            WidgetManager::instance()->registerFormWidget(FieldSetNoSaveStubWidget::class, 'fieldsetnosavestub');
+        }
+
+        protected function makeForm(): Form
+        {
+            return new Form(new Controller, [
+                'model' => new FormFieldSetSaveTestModel,
+                'arrayName' => 'array',
+                'fields' => [
+                    'top_level' => [
+                        'type' => 'text',
+                    ],
+                    'group' => [
+                        'type' => 'fieldset',
+                        'label' => 'Grouped Fields',
+                        'fields' => [
+                            'nested_text' => [
+                                'type' => 'text',
+                            ],
+                            'nested_number' => [
+                                'type' => 'number',
+                            ],
+                            'nested_widget' => [
+                                'type' => 'fieldsetsavestub',
+                            ],
+                            'nested_nosave' => [
+                                'type' => 'fieldsetnosavestub',
+                            ],
+                            'nested_disabled' => [
+                                'type' => 'text',
+                                'disabled' => true,
+                            ],
+                        ],
+                    ],
+                ],
+            ]);
+        }
+
+        /**
+         * getSaveData() reads its values with post(), which only returns real data when
+         * the request is genuinely a POST -- so simulate the postback first.
+         */
+        protected function postForm(array $data): array
+        {
+            request()->setMethod('POST');
+            request()->request->replace(['array' => $data]);
+
+            return $this->makeForm()->getSaveData();
+        }
+
+        public function testNestedFieldSetFieldsAreCollectedToParentLevel()
+        {
+            $data = $this->postForm([
+                'top_level' => 'top',
+                'nested_text' => 'hello',
+                'nested_number' => '42',
+            ]);
+
+            // Nested fields are hoisted to the parent save data...
+            $this->assertArrayHasKey('nested_text', $data);
+            $this->assertArrayHasKey('nested_number', $data);
+            $this->assertEquals('hello', $data['nested_text']);
+
+            // ...and the top level field is unaffected.
+            $this->assertEquals('top', $data['top_level']);
+
+            // The fieldset container itself must not be saved.
+            $this->assertArrayNotHasKey('group', $data);
+        }
+
+        public function testNestedNumberFieldIsCastToFloat()
+        {
+            $data = $this->postForm([
+                'nested_number' => '42',
+            ]);
+
+            $this->assertSame(42.0, $data['nested_number']);
+        }
+
+        public function testNestedNumberEmptyStringBecomesNull()
+        {
+            $data = $this->postForm([
+                'nested_number' => '   ',
+            ]);
+
+            $this->assertArrayHasKey('nested_number', $data);
+            $this->assertNull($data['nested_number']);
+        }
+
+        public function testNestedWidgetFieldHasSaveValueApplied()
+        {
+            $data = $this->postForm([
+                'nested_widget' => 'abc',
+            ]);
+
+            // The nested widget's getSaveValue() must be applied (stub upper-cases it),
+            // rather than the raw posted value being stored.
+            $this->assertArrayHasKey('nested_widget', $data);
+            $this->assertSame('ABC', $data['nested_widget']);
+        }
+
+        public function testNestedWidgetReturningNoSaveDataDoesNotLeakSentinel()
+        {
+            $data = $this->postForm([
+                'nested_nosave' => 'ignore me',
+            ]);
+
+            // A nested widget that returns NO_SAVE_DATA must behave exactly as it would
+            // at the top level of a form: the NO_SAVE_DATA sentinel (-1) must never be
+            // written to the model.
+            $this->assertNotSame(FormField::NO_SAVE_DATA, $data['nested_nosave'] ?? null);
+        }
+
+        public function testDisabledNestedFieldIsNotSaved()
+        {
+            $data = $this->postForm([
+                'nested_text' => 'hello',
+                'nested_disabled' => 'tampered',
+            ]);
+
+            // Disabled fields are omitted from the save data, just like top-level fields.
+            $this->assertArrayHasKey('nested_text', $data);
+            $this->assertArrayNotHasKey('nested_disabled', $data);
+        }
+
+        public function testMissingNestedValuesAreOmitted()
+        {
+            $data = $this->postForm([
+                'top_level' => 'top',
+            ]);
+
+            $this->assertArrayNotHasKey('nested_text', $data);
+            $this->assertArrayNotHasKey('nested_number', $data);
+        }
+    }
+}
diff --git a/modules/backend/widgets/Form.php b/modules/backend/widgets/Form.php
index 5598810d93..2fafa88a2f 100644
--- a/modules/backend/widgets/Form.php
+++ b/modules/backend/widgets/Form.php
@@ -1,17 +1,20 @@
-<?php namespace Backend\Widgets;
+<?php
+
+namespace Backend\Widgets;
 
-use ApplicationException;
 use Backend\Classes\FormField;
 use Backend\Classes\FormTabs;
 use Backend\Classes\FormWidgetBase;
 use Backend\Classes\WidgetBase;
 use Backend\Classes\WidgetManager;
-use BackendAuth;
+use Backend\Facades\BackendAuth;
+use Backend\FormWidgets\FieldSet;
 use Exception;
-use Form as FormHelper;
-use Lang;
+use Illuminate\Support\Facades\Lang;
 use Winter\Storm\Database\Model;
+use Winter\Storm\Exception\ApplicationException;
 use Winter\Storm\Html\Helper as HtmlHelper;
+use Winter\Storm\Support\Facades\Form as FormHelper;
 
 /**
  * Form Widget
@@ -1221,6 +1224,16 @@ public function getSaveData(): array
                 continue;
             }
 
+            // Fieldsets don't save a value of their own; their nested fields are saved
+            // to the model as if they were defined at this form's level. Delegating to
+            // the nested form's getSaveData() reuses all of its per-field processing.
+            if ($widget instanceof FieldSet) {
+                foreach ($widget->getSaveData() as $key => $value) {
+                    $this->dataArraySet($result, HtmlHelper::nameToArray($key), $value);
+                }
+                continue;
+            }
+
             // Exclude fields that didn't provide any value
             $fieldValue = $this->dataArrayGet($result, $parts, FormField::NO_SAVE_DATA);
             if ($fieldValue === FormField::NO_SAVE_DATA) {
@@ -1419,8 +1432,8 @@ protected function objectMethodExists($object, $method)
      *
      * @param array $array
      * @param array $parts
-     * @param null $default
-     * @return array|null
+     * @param mixed $default
+     * @return mixed
      */
     protected function dataArrayGet(array $array, array $parts, $default = null)
     {