diff --git a/packages/core/src/components/radio-group/index.ts b/packages/core/src/components/radio-group/index.ts
new file mode 100644
index 0000000..8701e3f
--- /dev/null
+++ b/packages/core/src/components/radio-group/index.ts
@@ -0,0 +1,12 @@
+import { useRadioGroupContext } from "./radio-group-context";
+import { RadioGroupItem } from "./radio-group-item";
+import { RadioGroupRoot } from "./radio-group-root";
+
+export const RadioGroup = Object.assign(RadioGroupRoot, {
+  Item: RadioGroupItem,
+  useContext: useRadioGroupContext,
+});
+
+export type { RadioGroupRootProps } from "./radio-group-root";
+export type { RadioGroupItemProps } from "./radio-group-item";
+export type { RadioGroupContextValue } from "./radio-group-context";
diff --git a/packages/core/src/components/radio-group/radio-group-context.ts b/packages/core/src/components/radio-group/radio-group-context.ts
new file mode 100644
index 0000000..7d39a46
--- /dev/null
+++ b/packages/core/src/components/radio-group/radio-group-context.ts
@@ -0,0 +1,27 @@
+import type { Accessor } from "solid-js";
+import { createContext, useContext } from "solid-js";
+
+export interface RadioGroupContextValue {
+  value: Accessor<string | undefined>;
+  onValueChange: (value: string) => void;
+  disabled: Accessor<boolean>;
+  name: Accessor<string | undefined>;
+}
+
+const RadioGroupContext = createContext<RadioGroupContextValue>();
+
+/**
+ * Returns the RadioGroup context. Throws if used outside <RadioGroup>.
+ */
+export function useRadioGroupContext(): RadioGroupContextValue {
+  const ctx = useContext(RadioGroupContext);
+  if (!ctx) {
+    throw new Error(
+      "[PettyUI] RadioGroup.Item must be used inside <RadioGroup>.\n" +
+        "  Fix: Wrap RadioGroup.Item elements inside <RadioGroup>.",
+    );
+  }
+  return ctx;
+}
+
+export const RadioGroupContextProvider = RadioGroupContext.Provider;
diff --git a/packages/core/src/components/radio-group/radio-group-item.tsx b/packages/core/src/components/radio-group/radio-group-item.tsx
new file mode 100644
index 0000000..60071f9
--- /dev/null
+++ b/packages/core/src/components/radio-group/radio-group-item.tsx
@@ -0,0 +1,61 @@
+import type { JSX } from "solid-js";
+import { splitProps } from "solid-js";
+import { useRadioGroupContext } from "./radio-group-context";
+
+export interface RadioGroupItemProps extends JSX.ButtonHTMLAttributes<HTMLButtonElement> {
+  value: string;
+  disabled?: boolean;
+  children?: JSX.Element;
+}
+
+/**
+ * A single radio option within a RadioGroup.
+ * Arrow keys navigate between items; clicking selects.
+ */
+export function RadioGroupItem(props: RadioGroupItemProps): JSX.Element {
+  const [local, rest] = splitProps(props, ["value", "disabled", "children"]);
+  const ctx = useRadioGroupContext();
+
+  const isChecked = () => ctx.value() === local.value;
+  const isDisabled = () => local.disabled || ctx.disabled();
+
+  return (
+    <button
+      type="button"
+      role="radio"
+      aria-checked={isChecked()}
+      data-state={isChecked() ? "checked" : "unchecked"}
+      disabled={isDisabled()}
+      tabIndex={isChecked() ? 0 : -1}
+      {...rest}
+      onClick={(e) => {
+        if (typeof rest.onClick === "function") rest.onClick(e);
+        if (!isDisabled()) ctx.onValueChange(local.value);
+      }}
+      onKeyDown={(e) => {
+        if (typeof rest.onKeyDown === "function") rest.onKeyDown(e);
+        if (isDisabled()) return;
+
+        const group = (e.currentTarget as HTMLButtonElement).closest("[role='radiogroup']");
+        if (!group) return;
+
+        const items = Array.from(
+          group.querySelectorAll<HTMLButtonElement>("[role='radio']:not([disabled])"),
+        );
+        const index = items.indexOf(e.currentTarget as HTMLButtonElement);
+
+        if (e.key === "ArrowDown" || e.key === "ArrowRight") {
+          e.preventDefault();
+          const next = items[(index + 1) % items.length];
+          next?.focus();
+        } else if (e.key === "ArrowUp" || e.key === "ArrowLeft") {
+          e.preventDefault();
+          const prev = items[(index - 1 + items.length) % items.length];
+          prev?.focus();
+        }
+      }}
+    >
+      {local.children}
+    </button>
+  );
+}
diff --git a/packages/core/src/components/radio-group/radio-group-root.tsx b/packages/core/src/components/radio-group/radio-group-root.tsx
new file mode 100644
index 0000000..1990baf
--- /dev/null
+++ b/packages/core/src/components/radio-group/radio-group-root.tsx
@@ -0,0 +1,57 @@
+import type { JSX } from "solid-js";
+import { splitProps } from "solid-js";
+import { createControllableSignal } from "../../primitives/create-controllable-signal";
+import { RadioGroupContextProvider, type RadioGroupContextValue } from "./radio-group-context";
+
+export interface RadioGroupRootProps extends JSX.HTMLAttributes<HTMLDivElement> {
+  value?: string;
+  defaultValue?: string;
+  onValueChange?: (value: string) => void;
+  disabled?: boolean;
+  name?: string;
+  orientation?: "horizontal" | "vertical";
+  children: JSX.Element;
+}
+
+/**
+ * Root container for a group of mutually exclusive radio buttons.
+ */
+export function RadioGroupRoot(props: RadioGroupRootProps): JSX.Element {
+  const [local, rest] = splitProps(props, [
+    "value",
+    "defaultValue",
+    "onValueChange",
+    "disabled",
+    "name",
+    "orientation",
+    "children",
+  ]);
+
+  const [selectedValue, setSelectedValue] = createControllableSignal<string | undefined>({
+    value: () => local.value,
+    defaultValue: () => local.defaultValue,
+    onChange: (v) => {
+      if (v !== undefined) local.onValueChange?.(v);
+    },
+  });
+
+  const ctx: RadioGroupContextValue = {
+    value: selectedValue,
+    onValueChange: (v) => setSelectedValue(v),
+    disabled: () => local.disabled ?? false,
+    name: () => local.name,
+  };
+
+  return (
+    <RadioGroupContextProvider value={ctx}>
+      <div
+        role="radiogroup"
+        aria-orientation={local.orientation}
+        data-disabled={local.disabled || undefined}
+        {...rest}
+      >
+        {local.children}
+      </div>
+    </RadioGroupContextProvider>
+  );
+}
diff --git a/packages/core/tests/components/radio-group/radio-group.test.tsx b/packages/core/tests/components/radio-group/radio-group.test.tsx
new file mode 100644
index 0000000..d9a1425
--- /dev/null
+++ b/packages/core/tests/components/radio-group/radio-group.test.tsx
@@ -0,0 +1,90 @@
+import { fireEvent, render, screen } from "@solidjs/testing-library";
+import { describe, expect, it } from "vitest";
+import { RadioGroup } from "../../../src/components/radio-group/index";
+
+describe("RadioGroup", () => {
+  it("renders with role=radiogroup", () => {
+    render(() => (
+      <RadioGroup>
+        <RadioGroup.Item value="a">A</RadioGroup.Item>
+      </RadioGroup>
+    ));
+    expect(screen.getByRole("radiogroup")).toBeTruthy();
+  });
+
+  it("items have role=radio", () => {
+    render(() => (
+      <RadioGroup>
+        <RadioGroup.Item value="a">A</RadioGroup.Item>
+        <RadioGroup.Item value="b">B</RadioGroup.Item>
+      </RadioGroup>
+    ));
+    expect(screen.getAllByRole("radio")).toHaveLength(2);
+  });
+
+  it("no item is checked by default", () => {
+    render(() => (
+      <RadioGroup>
+        <RadioGroup.Item value="a">A</RadioGroup.Item>
+      </RadioGroup>
+    ));
+    expect(screen.getByRole("radio").getAttribute("aria-checked")).toBe("false");
+  });
+
+  it("defaultValue pre-selects item", () => {
+    render(() => (
+      <RadioGroup defaultValue="b">
+        <RadioGroup.Item value="a">A</RadioGroup.Item>
+        <RadioGroup.Item value="b">B</RadioGroup.Item>
+      </RadioGroup>
+    ));
+    const radios = screen.getAllByRole("radio");
+    expect(radios[0].getAttribute("aria-checked")).toBe("false");
+    expect(radios[1].getAttribute("aria-checked")).toBe("true");
+  });
+
+  it("clicking an item selects it", () => {
+    render(() => (
+      <RadioGroup>
+        <RadioGroup.Item value="a">A</RadioGroup.Item>
+        <RadioGroup.Item value="b">B</RadioGroup.Item>
+      </RadioGroup>
+    ));
+    fireEvent.click(screen.getAllByRole("radio")[0]);
+    expect(screen.getAllByRole("radio")[0].getAttribute("aria-checked")).toBe("true");
+    expect(screen.getAllByRole("radio")[1].getAttribute("aria-checked")).toBe("false");
+  });
+
+  it("clicking a selected item keeps it selected", () => {
+    render(() => (
+      <RadioGroup defaultValue="a">
+        <RadioGroup.Item value="a">A</RadioGroup.Item>
+      </RadioGroup>
+    ));
+    fireEvent.click(screen.getByRole("radio"));
+    expect(screen.getByRole("radio").getAttribute("aria-checked")).toBe("true");
+  });
+
+  it("ArrowDown moves to next radio", () => {
+    render(() => (
+      <RadioGroup>
+        <RadioGroup.Item value="a">A</RadioGroup.Item>
+        <RadioGroup.Item value="b">B</RadioGroup.Item>
+      </RadioGroup>
+    ));
+    const [first] = screen.getAllByRole("radio");
+    first.focus();
+    fireEvent.keyDown(first, { key: "ArrowDown" });
+    expect(document.activeElement).toBe(screen.getAllByRole("radio")[1]);
+  });
+
+  it("disabled item is not selectable", () => {
+    render(() => (
+      <RadioGroup>
+        <RadioGroup.Item value="a" disabled>A</RadioGroup.Item>
+      </RadioGroup>
+    ));
+    fireEvent.click(screen.getByRole("radio"));
+    expect(screen.getByRole("radio").getAttribute("aria-checked")).toBe("false");
+  });
+});