diff --git a/change/@fluentui-web-components-7441a75d-cb13-41f1-a772-07b6ea6d14d4.json b/change/@fluentui-web-components-7441a75d-cb13-41f1-a772-07b6ea6d14d4.json
new file mode 100644
index 00000000000000..e3d0387fd61263
--- /dev/null
+++ b/change/@fluentui-web-components-7441a75d-cb13-41f1-a772-07b6ea6d14d4.json
@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "Fix `spellcheck` conversion and propagation for TextInput and TextArea.",
+  "packageName": "@fluentui/web-components",
+  "email": "863023+radium-v@users.noreply.github.com",
+  "dependentChangeType": "patch"
+}
diff --git a/packages/web-components/src/text-input/text-input.base.ts b/packages/web-components/src/text-input/text-input.base.ts
index 4a2f08be10eb9c..b68106116930ab 100644
--- a/packages/web-components/src/text-input/text-input.base.ts
+++ b/packages/web-components/src/text-input/text-input.base.ts
@@ -270,8 +270,8 @@ export class BaseTextInput extends FASTElement {
    */
   @attr({
     converter: {
-      fromView: value => (typeof value === 'string' ? ['true', ''].includes(value.trim().toLowerCase()) : null),
-      toView: value => value.toString(),
+      fromView: value => (typeof value === 'string' ? ['true', ''].includes(value.trim().toLowerCase()) : value),
+      toView: value => (value === null || value === undefined ? null : value.toString()),
     },
   })
   public spellcheck!: boolean;
diff --git a/packages/web-components/src/text-input/text-input.spec.ts b/packages/web-components/src/text-input/text-input.spec.ts
index 190f4966a94651..e72265b92caaf4 100644
--- a/packages/web-components/src/text-input/text-input.spec.ts
+++ b/packages/web-components/src/text-input/text-input.spec.ts
@@ -61,13 +61,101 @@ test.describe('TextInput', () => {
     await expect(control).toHaveAttribute('required');
   });
 
-  test('should set the `spellcheck` attribute on the internal control', async ({ fastPage }) => {
-    const { element } = fastPage;
-    const control = element.locator('input');
+  test.describe('spellcheck', () => {
+    const attributeCases = [
+      { value: 'true', expected: true },
+      { value: 'false', expected: false },
+      { value: '', expected: true },
+      { value: 'anything', expected: false },
+    ] as const;
+
+    for (const { value, expected } of attributeCases) {
+      test(`should propagate \`spellcheck="${value}"\` to the internal control`, async ({ fastPage }) => {
+        const { element } = fastPage;
+        const control = element.locator('input');
+
+        await fastPage.setTemplate(/* html */ `
+          <div spellcheck="false">
+            <${tagName}></${tagName}>
+          </div>
+        `);
+
+        await element.evaluate((node, attributeValue) => {
+          node.setAttribute('spellcheck', attributeValue);
+        }, value);
+
+        await expect(element).toHaveAttribute('spellcheck', value);
+        await expect(element).toHaveJSProperty('spellcheck', expected);
+        await expect(control).toHaveAttribute('spellcheck', expected.toString());
+        await expect(control).toHaveJSProperty('spellcheck', expected);
+      });
+    }
+
+    for (const spellcheck of [true, false]) {
+      test(`should propagate a ${spellcheck} \`spellcheck\` property to the internal control`, async ({ fastPage }) => {
+        const { element } = fastPage;
+        const control = element.locator('input');
 
-    await fastPage.setTemplate({ attributes: { spellcheck: 'true' } });
+        await fastPage.setTemplate();
+
+        await element.evaluate((node: TextInput, value) => {
+          node.spellcheck = value;
+        }, spellcheck);
+
+        await expect(element).toHaveAttribute('spellcheck', spellcheck.toString());
+        await expect(element).toHaveJSProperty('spellcheck', spellcheck);
+        await expect(control).toHaveAttribute('spellcheck', spellcheck.toString());
+        await expect(control).toHaveJSProperty('spellcheck', spellcheck);
+      });
+    }
 
-    await expect(control).toHaveAttribute('spellcheck', 'true');
+    for (const value of ['null', 'undefined'] as const) {
+      test(`should propagate a ${value} \`spellcheck\` property to the internal control`, async ({ fastPage }) => {
+        const { element } = fastPage;
+        const control = element.locator('input');
+
+        await fastPage.setTemplate();
+
+        await element.evaluate((node, nullishValue) => {
+          Reflect.set(node, 'spellcheck', nullishValue === 'null' ? null : undefined);
+        }, value);
+
+        await expect(element).not.toHaveAttribute('spellcheck');
+        await expect(element).toHaveJSProperty('spellcheck', value === 'null' ? null : undefined);
+        await expect(control).not.toHaveAttribute('spellcheck');
+      });
+    }
+
+    test('should propagate removal of the host `spellcheck` attribute to the internal control', async ({
+      fastPage,
+    }) => {
+      const { element } = fastPage;
+      const control = element.locator('input');
+
+      await fastPage.setTemplate(/* html */ `
+        <div spellcheck="false">
+          <${tagName} spellcheck="true"></${tagName}>
+        </div>
+      `);
+
+      await element.evaluate(node => {
+        node.removeAttribute('spellcheck');
+      });
+
+      await expect(element).not.toHaveAttribute('spellcheck');
+      await expect(element).toHaveJSProperty('spellcheck', null);
+      await expect(control).not.toHaveAttribute('spellcheck');
+    });
+
+    test('should use the browser default when `spellcheck` is unset', async ({ fastPage }) => {
+      const { element } = fastPage;
+      const control = element.locator('input');
+
+      await fastPage.setTemplate();
+
+      await expect(element).not.toHaveAttribute('spellcheck');
+      await expect(control).not.toHaveAttribute('spellcheck');
+    });
   });
 
   test('should set the `maxlength` attribute on the internal control', async ({ fastPage }) => {
diff --git a/packages/web-components/src/textarea/textarea.base.ts b/packages/web-components/src/textarea/textarea.base.ts
index e0cbb42deb7e7c..0e264e415d58bc 100644
--- a/packages/web-components/src/textarea/textarea.base.ts
+++ b/packages/web-components/src/textarea/textarea.base.ts
@@ -61,6 +61,8 @@ export class BaseTextArea extends FASTElement {
    * @internal
    */
   protected controlElChanged() {
+    this.controlEl.spellcheck = this.spellcheck;
+
     this.controlElAttrObserver = new MutationObserver(() => {
       this.setValidity();
     });
@@ -316,7 +318,12 @@ export class BaseTextArea extends FASTElement {
    * @remarks
    * HTML Attribute: `spellcheck`
    */
-  @attr({ mode: 'boolean' })
+  @attr({
+    converter: {
+      fromView: value => (typeof value === 'string' ? ['true', ''].includes(value.trim().toLowerCase()) : value),
+      toView: value => (value === null || value === undefined ? null : value.toString()),
+    },
+  })
   public spellcheck = false;
 
   /**
diff --git a/packages/web-components/src/textarea/textarea.spec.ts b/packages/web-components/src/textarea/textarea.spec.ts
index 30e41542c091bb..e92a9de7879824 100644
--- a/packages/web-components/src/textarea/textarea.spec.ts
+++ b/packages/web-components/src/textarea/textarea.spec.ts
@@ -51,7 +51,6 @@ test.describe('TextArea', () => {
         required: true,
         disabled: true,
         readonly: true,
-        spellcheck: true,
         autocomplete: 'on',
         maxlength: '100',
         minlength: '10',
@@ -62,13 +61,111 @@ test.describe('TextArea', () => {
     await expect(control).toHaveJSProperty('required', true);
     await expect(control).toHaveJSProperty('disabled', true);
     await expect(control).toHaveJSProperty('readOnly', true);
-    await expect(control).toHaveJSProperty('spellcheck', true);
     await expect(control).toHaveJSProperty('autocomplete', 'on');
     await expect(control).toHaveJSProperty('maxLength', 100);
     await expect(control).toHaveJSProperty('minLength', 10);
     await expect(control).toHaveJSProperty('placeholder', 'Placeholder');
   });
 
+  test.describe('spellcheck', () => {
+    const attributeCases = [
+      { value: 'true', expected: true },
+      { value: 'false', expected: false },
+      { value: '', expected: true },
+      { value: 'anything', expected: false },
+    ] as const;
+
+    for (const { value, expected } of attributeCases) {
+      test(`should propagate \`spellcheck="${value}"\` to the internal control`, async ({ fastPage }) => {
+        const { element } = fastPage;
+        const control = element.locator('textarea');
+
+        await fastPage.setTemplate(/* html */ `
+          <div spellcheck="false">
+            <${tagName}></${tagName}>
+          </div>
+        `);
+
+        await element.evaluate((node, attributeValue) => {
+          node.setAttribute('spellcheck', attributeValue);
+        }, value);
+
+        await expect(element).toHaveAttribute('spellcheck', value);
+        await expect(element).toHaveJSProperty('spellcheck', expected);
+        await expect(control).toHaveAttribute('spellcheck', expected.toString());
+        await expect(control).toHaveJSProperty('spellcheck', expected);
+      });
+    }
+
+    for (const spellcheck of [true, false]) {
+      test(`should propagate a ${spellcheck} \`spellcheck\` property to the internal control`, async ({ fastPage }) => {
+        const { element } = fastPage;
+        const control = element.locator('textarea');
+
+        await fastPage.setTemplate();
+
+        await element.evaluate((node: HTMLElement, value) => {
+          node.spellcheck = value;
+        }, spellcheck);
+
+        await expect(element).toHaveAttribute('spellcheck', spellcheck.toString());
+        await expect(element).toHaveJSProperty('spellcheck', spellcheck);
+        await expect(control).toHaveAttribute('spellcheck', spellcheck.toString());
+        await expect(control).toHaveJSProperty('spellcheck', spellcheck);
+      });
+    }
+
+    for (const value of ['null', 'undefined'] as const) {
+      test(`should propagate a ${value} \`spellcheck\` property to the internal control`, async ({ fastPage }) => {
+        const { element } = fastPage;
+        const control = element.locator('textarea');
+
+        await fastPage.setTemplate();
+
+        await element.evaluate((node, nullishValue) => {
+          Reflect.set(node, 'spellcheck', nullishValue === 'null' ? null : undefined);
+        }, value);
+
+        await expect(element).not.toHaveAttribute('spellcheck');
+        await expect(element).toHaveJSProperty('spellcheck', value === 'null' ? null : undefined);
+        await expect(control).not.toHaveAttribute('spellcheck');
+      });
+    }
+
+    test('should propagate removal of the host `spellcheck` attribute to the internal control', async ({
+      fastPage,
+    }) => {
+      const { element } = fastPage;
+      const control = element.locator('textarea');
+
+      await fastPage.setTemplate(/* html */ `
+        <div spellcheck="false">
+          <${tagName} spellcheck="true"></${tagName}>
+        </div>
+      `);
+
+      await element.evaluate(node => {
+        node.removeAttribute('spellcheck');
+      });
+
+      await expect(element).not.toHaveAttribute('spellcheck');
+      await expect(element).toHaveJSProperty('spellcheck', null);
+      await expect(control).not.toHaveAttribute('spellcheck');
+    });
+
+    test('should use the browser default when `spellcheck` is unset', async ({ fastPage }) => {
+      const { element } = fastPage;
+      const control = element.locator('textarea');
+
+      await fastPage.setTemplate();
+
+      await expect(element).toHaveAttribute('spellcheck', 'false');
+      await expect(element).toHaveJSProperty('spellcheck', false);
+      await expect(control).toHaveAttribute('spellcheck', 'false');
+      await expect(control).toHaveJSProperty('spellcheck', false);
+    });
+  });
+
   test('should be associated with the given external labels', async ({ fastPage, page }) => {
     const { element } = fastPage;
 
diff --git a/packages/web-components/src/textarea/textarea.stories.ts b/packages/web-components/src/textarea/textarea.stories.ts
index ab90fef6d4a1a2..adfb5085a7d721 100644
--- a/packages/web-components/src/textarea/textarea.stories.ts
+++ b/packages/web-components/src/textarea/textarea.stories.ts
@@ -25,7 +25,7 @@ const storyTemplate = html<StoryArgs<FluentTextArea>>`
     ?readonly="${x => x.readOnly}"
     ?required="${x => x.required}"
     size="${x => x.size}"
-    ?spellcheck="${x => x.spellcheck}"
+    spellcheck="${x => x.spellcheck}"
     resize="${x => x.resize}"
     value="${x => x.value}"
   >
diff --git a/packages/web-components/src/textarea/textarea.template.html b/packages/web-components/src/textarea/textarea.template.html
index 83216b4cecdf6e..5c8f55c73d546e 100644
--- a/packages/web-components/src/textarea/textarea.template.html
+++ b/packages/web-components/src/textarea/textarea.template.html
@@ -13,7 +13,7 @@
         ?required="{{required}}"
         ?disabled="{{disabled}}"
         ?readonly="{{readOnly}}"
-        ?spellcheck="{{spellcheck}}"
+        spellcheck="{{spellcheck}}"
         autocomplete="{{autocomplete}}"
         maxlength="{{maxLength}}"
         minlength="{{minLength}}"
diff --git a/packages/web-components/src/textarea/textarea.template.ts b/packages/web-components/src/textarea/textarea.template.ts
index f8bf158c9912cc..cc97b3a038aa14 100644
--- a/packages/web-components/src/textarea/textarea.template.ts
+++ b/packages/web-components/src/textarea/textarea.template.ts
@@ -21,7 +21,7 @@ export function textAreaTemplate<T extends TextArea>(): ElementViewTemplate<T> {
           ?required="${x => x.required}"
           ?disabled="${x => x.disabled}"
           ?readonly="${x => x.readOnly}"
-          ?spellcheck="${x => x.spellcheck}"
+          spellcheck="${x => x.spellcheck}"
           autocomplete="${x => x.autocomplete}"
           maxlength="${x => x.maxLength}"
           minlength="${x => x.minLength}"