diff --git a/src/lib/components/form/Form.component.tsx b/src/lib/components/form/Form.component.tsx
index 750034c179..a45bda71b5 100644
--- a/src/lib/components/form/Form.component.tsx
+++ b/src/lib/components/form/Form.component.tsx
@@ -35,9 +35,8 @@ type FormProps = Omit<
    * overflowing. It also lays each `FormSection` out as a two-column grid that
    * auto-flips to a stacked single column on narrow widths — there is no
    * breakpoint prop; the flip point is derived from the layout (see below).
-   * Note: only `Input` currently honors the fluid width — `Select`, `SearchInput`,
-   * `TextArea` and other size-driven content keep their fixed width for now
-   * (tracked in CUI-36).
+   * Note: `Input` and `Select` currently honor the fluid width — `SearchInput`,
+   * `TextArea` and other size-driven content keep their fixed width for now.
    */
   responsive?: boolean;
 };
@@ -339,7 +338,20 @@ const FormGroup = ({
     <Stack
       direction={helpErrorPosition === 'right' ? 'horizontal' : 'vertical'}
       gap={helpErrorPosition === 'right' ? 'r8' : 'r4'}
-      style={responsive ? { minWidth: 0 } : undefined}
+      style={
+        responsive
+          ? {
+              minWidth: 0,
+              // Left-align rather than stretch, so a width-less control (a
+              // TextArea sized only by its `cols`) keeps its intrinsic size in
+              // the fluid `1fr` field column instead of growing to fill it.
+              // Input is unaffected — it caps itself via `max-width: 100%`.
+              ...(helpErrorPosition === 'right'
+                ? {}
+                : { alignItems: 'flex-start' }),
+            }
+          : undefined
+      }
     >
       {content}
       {error ? (
@@ -379,9 +391,11 @@ type FormSectionProps = {
   children: ReactElement<FormGroupProps> | ReactElement<FormGroupProps>[];
   title?: { name: string; icon?: IconName; helpTooltip?: string };
   /**
-   * Freezes the label column to exactly this pixel width — a hard cap: labels
-   * wider than it wrap rather than widening the column. When unset, the column
-   * auto-sizes to the widest label in the section.
+   * Caps the label column at this pixel width: labels wider than it wrap rather
+   * than widening the column. In a `responsive` Form the column keeps this width
+   * while there is room but shrinks below it (down to the longest word) as the
+   * field track is squeezed, so rows stay aligned; otherwise it is pinned to this
+   * exact width. When unset, the column auto-sizes to the widest label.
    */
   forceLabelWidth?: number;
   rightActions?: ReactNode;
@@ -399,20 +413,19 @@ const FormSection = ({
     isValidElement(child) ? child.props.required === true : false,
   );
 
-  // The label column. `forceLabelWidth` is a hard cap that freezes it to an exact
-  // pixel width (long labels then wrap, mirroring how `Input`'s `size` fixes the
-  // field width); it also makes every FormGroup row self-sufficient, so nesting a
-  // group inside another element no longer breaks its layout. When unset, the
-  // column auto-sizes to the widest label from content, shared across rows via
-  // `subgrid` — no measurement. Responsive lets the track shrink to its longest
-  // word (min-content) before the section flips; non-responsive hugs it
-  // (max-content).
+  // The label column. `forceLabelWidth` sets the column's upper bound to an exact
+  // pixel width (labels wider than it wrap, mirroring how `Input`'s `size` fixes
+  // the field width); it also makes every FormGroup row self-sufficient, so nesting
+  // a group inside another element no longer breaks its layout. When unset, the
+  // column's cap is its widest label (`max-content`), shared across rows via
+  // `subgrid` — no measurement. Responsive then lets the column shrink from its
+  // longest word (`min-content`) up to that cap before the section flips;
+  // non-responsive pins it to the cap.
   const fixedLabel = forceLabelWidth != null;
-  const labelTrack = fixedLabel
-    ? `${forceLabelWidth}px`
-    : responsive
-      ? 'minmax(min-content, max-content)'
-      : 'max-content';
+  const labelWidthCap = fixedLabel ? `${forceLabelWidth}px` : 'max-content';
+  const labelTrack = responsive
+    ? `minmax(min-content, ${labelWidthCap})`
+    : labelWidthCap;
 
   return (
     <FormSectionContext.Provider value={{ labelTrack, fixedLabel }}>
diff --git a/src/lib/components/selectv2/SelectStyle.ts b/src/lib/components/selectv2/SelectStyle.ts
index df49b961c6..706df0cb61 100644
--- a/src/lib/components/selectv2/SelectStyle.ts
+++ b/src/lib/components/selectv2/SelectStyle.ts
@@ -8,6 +8,7 @@ const SelectStyle = styled(Select)`
   font-size: ${fontSize.base};
   box-sizing: border-box;
   width: ${({ width }) => width};
+  ${({ fluid }) => fluid && `max-width: 100%; min-width: 0;`}
   ${({ isDefault }) =>
     isDefault ? `height: ${spacing.r32}` : `height: ${spacing.r24}`};
 
@@ -122,7 +123,7 @@ const SelectStyle = styled(Select)`
   }
 
   .sc-select__menu {
-    width: ${({ width }) => width};
+    width: ${({ fluid, width }) => (fluid ? '100%' : width)};
     border: ${spacing.r1} solid
       ${({ isDefault }) =>
         getThemePropSelector(isDefault ? 'border' : 'selectedActive')};
diff --git a/src/lib/components/selectv2/Selectv2.component.tsx b/src/lib/components/selectv2/Selectv2.component.tsx
index c7d1f5277e..cc3e7d6dcf 100644
--- a/src/lib/components/selectv2/Selectv2.component.tsx
+++ b/src/lib/components/selectv2/Selectv2.component.tsx
@@ -27,6 +27,7 @@ import { FixedSizeList, FixedSizeList as List } from 'react-window';
 import { convertRemToPixels } from '../../utils';
 import { spacing } from '../../spacing';
 import { convertSizeToRem } from '../inputv2/inputv2';
+import { useFieldContext } from '../form/Form.component';
 import { ConstrainedText } from '../constrainedtext/Constrainedtext.component';
 import ReactSelect from 'react-select/src/Select';
 
@@ -348,6 +349,9 @@ export type SelectProps = {
   variant?: 'default' | 'rounded';
   size?: '1' | '2/3' | '1/2' | '1/3';
   className?: string;
+  /** When true (or inside a responsive Form), the control fills its container
+   *  down to a min instead of staying fixed at its `size` width. */
+  fluid?: boolean;
   /** use menuPositon='fixed' inside modal to avoid display issue */
   menuPosition?: 'fixed' | 'absolute';
   /** number of items visible before the option list becomes scrollable
@@ -395,11 +399,14 @@ function SelectBox<
   size = '1',
   id,
   selectRef,
+  fluid,
   itemsPerScrollWindow = 4,
   ...rest
 }: SelectProps & {
   selectRef?: Ref<SelectRef<OptionType, IsMulti, GroupType>>;
 }) {
+  const { responsive: responsiveFromFieldContext } = useFieldContext();
+  const isFluid = !!(fluid || responsiveFromFieldContext);
   const [keyboardFocusEnabled, setKeyboardFocusEnabled] = useState(false);
   const [searchSelection, setSearchSelection] = useState('');
   const [searchValue, setSearchValue] = useState('');
@@ -571,6 +578,7 @@ function SelectBox<
               }
             }}
             width={convertSizeToRem(size)}
+            fluid={isFluid}
             {...rest}
           />
         )}
@@ -599,11 +607,14 @@ const SelectWithOptionContext = forwardRef<
     });
   }, []);
 
-  const contextValue = useMemo(() => ({
-    options, 
-    register, 
-    unregister
-  }), [options, register, unregister]);
+  const contextValue = useMemo(
+    () => ({
+      options,
+      register,
+      unregister,
+    }),
+    [options, register, unregister],
+  );
 
   return (
     <OptionContext.Provider value={contextValue}>