diff --git a/docs/pages/api-docs/autocomplete.md b/docs/pages/api-docs/autocomplete.md
index cada927311c2c0..2b7dc58e2a14d5 100644
--- a/docs/pages/api-docs/autocomplete.md
+++ b/docs/pages/api-docs/autocomplete.md
@@ -50,6 +50,7 @@ The `MuiAutocomplete` name can be used for providing [default props](/customizat
 | <span class="prop-name">filterSelectedOptions</span> | <span class="prop-type">bool</span> | <span class="prop-default">false</span> | If `true`, hide the selected options from the list box. |
 | <span class="prop-name">forcePopupIcon</span> | <span class="prop-type">'auto'<br>&#124;&nbsp;bool</span> | <span class="prop-default">'auto'</span> | Force the visibility display of the popup icon. |
 | <span class="prop-name">freeSolo</span> | <span class="prop-type">bool</span> | <span class="prop-default">false</span> | If `true`, the Autocomplete is free solo, meaning that the user input is not bound to provided options. |
+| <span class="prop-name">fullWidth</span> | <span class="prop-type">bool</span> | <span class="prop-default">false</span> | If `true`, the input will take up the full width of its container. |
 | <span class="prop-name">getLimitTagsText</span> | <span class="prop-type">func</span> | <span class="prop-default">(more) => `+${more}`</span> | The label to display when the tags are truncated (`limitTags`).<br><br>**Signature:**<br>`function(more: number) => ReactNode`<br>*more:* The number of truncated tags. |
 | <span class="prop-name">getOptionDisabled</span> | <span class="prop-type">func</span> |  | Used to determine the disabled state for a given option. |
 | <span class="prop-name">getOptionLabel</span> | <span class="prop-type">func</span> | <span class="prop-default">(x) => x</span> | Used to determine the string value for a given option. It's used to fill the input (and the list box options if `renderOption` is not provided). |
@@ -93,6 +94,7 @@ Any other props supplied will be provided to the root element (native element).
 | Rule name | Global class | Description |
 |:-----|:-------------|:------------|
 | <span class="prop-name">root</span> | <span class="prop-name">.MuiAutocomplete-root</span> | Styles applied to the root element.
+| <span class="prop-name">fullWidth</span> | <span class="prop-name">.MuiAutocomplete-fullWidth</span> | Styles applied to the root element if `fullWidth={true}`.
 | <span class="prop-name">focused</span> | <span class="prop-name">.Mui-focused</span> | Pseudo-class applied to the root element if focused.
 | <span class="prop-name">tag</span> | <span class="prop-name">.MuiAutocomplete-tag</span> | Styles applied to the tag elements, e.g. the chips.
 | <span class="prop-name">tagSizeSmall</span> | <span class="prop-name">.MuiAutocomplete-tagSizeSmall</span> | Styles applied to the tag elements, e.g. the chips if `size="small"`.
diff --git a/packages/material-ui-lab/src/Autocomplete/Autocomplete.d.ts b/packages/material-ui-lab/src/Autocomplete/Autocomplete.d.ts
index d5a61410dd626a..c49a4a584fb993 100644
--- a/packages/material-ui-lab/src/Autocomplete/Autocomplete.d.ts
+++ b/packages/material-ui-lab/src/Autocomplete/Autocomplete.d.ts
@@ -84,6 +84,10 @@ export interface AutocompleteProps<T>
    * Force the visibility display of the popup icon.
    */
   forcePopupIcon?: true | false | 'auto';
+  /**
+   * If `true`, the input will take up the full width of its container.
+   */
+  fullWidth?: boolean;
   /**
    * The label to display when the tags are truncated (`limitTags`).
    *
diff --git a/packages/material-ui-lab/src/Autocomplete/Autocomplete.js b/packages/material-ui-lab/src/Autocomplete/Autocomplete.js
index 1c024954e11522..6234cba2f21941 100644
--- a/packages/material-ui-lab/src/Autocomplete/Autocomplete.js
+++ b/packages/material-ui-lab/src/Autocomplete/Autocomplete.js
@@ -20,6 +20,10 @@ export const styles = (theme) => ({
       visibility: 'visible',
     },
   },
+  /* Styles applied to the root element if `fullWidth={true}`. */
+  fullWidth: {
+    width: '100%',
+  },
   /* Pseudo-class applied to the root element if focused. */
   focused: {},
   /* Styles applied to the tag elements, e.g. the chips. */
@@ -256,6 +260,7 @@ const Autocomplete = React.forwardRef(function Autocomplete(props, ref) {
     filterSelectedOptions = false,
     forcePopupIcon = 'auto',
     freeSolo = false,
+    fullWidth = false,
     getLimitTagsText = (more) => `+${more}`,
     getOptionDisabled,
     getOptionLabel = (x) => x,
@@ -389,6 +394,7 @@ const Autocomplete = React.forwardRef(function Autocomplete(props, ref) {
           classes.root,
           {
             [classes.focused]: focused,
+            [classes.fullWidth]: fullWidth,
             [classes.hasClearIcon]: hasClearIcon,
             [classes.hasPopupIcon]: hasPopupIcon,
           },
@@ -610,6 +616,10 @@ Autocomplete.propTypes = {
    * If `true`, the Autocomplete is free solo, meaning that the user input is not bound to provided options.
    */
   freeSolo: PropTypes.bool,
+  /**
+   * If `true`, the input will take up the full width of its container.
+   */
+  fullWidth: PropTypes.bool,
   /**
    * The label to display when the tags are truncated (`limitTags`).
    *
diff --git a/packages/material-ui-lab/src/Autocomplete/Autocomplete.test.js b/packages/material-ui-lab/src/Autocomplete/Autocomplete.test.js
index a2370f367739ed..4c5ef3ae40633e 100644
--- a/packages/material-ui-lab/src/Autocomplete/Autocomplete.test.js
+++ b/packages/material-ui-lab/src/Autocomplete/Autocomplete.test.js
@@ -1512,4 +1512,20 @@ describe('<Autocomplete />', () => {
       expect(options).to.have.length(3);
     });
   });
+
+  describe('prop: fullWidth', () => {
+    it('should have the fullWidth class', () => {
+      const { container } = render(
+        <Autocomplete
+          {...defaultProps}
+          fullWidth
+          options={[0, 10, 20]}
+          renderInput={(params) => <TextField {...params} />}
+          value={null}
+        />,
+      );
+
+      expect(container.querySelector(`.${classes.root}`)).to.have.class(classes.fullWidth);
+    });
+  });
 });