diff --git a/__tests__/lib/mdxish/variables-code.test.ts b/__tests__/lib/mdxish/variables-code.test.ts
index a6cd91b1d..220efb88f 100644
--- a/__tests__/lib/mdxish/variables-code.test.ts
+++ b/__tests__/lib/mdxish/variables-code.test.ts
@@ -108,6 +108,36 @@ const name = 'Bearer ${variable}';
     expect(getCodeText(tree)).toBe('sk_live_123');
   });
 
+  it('stringifies structured variables in code', () => {
+    const tree = mdxish('`<<keys>> {user.profile} {user.limit} {user.active}`', {
+      variables: {
+        user: {
+          active: true,
+          keys: [{ apiKey: 'rdme_123' }],
+          limit: 25,
+          profile: { plan: 'enterprise' },
+        },
+        defaults: [],
+      },
+    });
+
+    expect(getCodeText(tree)).toBe('[{"apiKey":"rdme_123"}] {"plan":"enterprise"} 25 true');
+  });
+
+  it('coerces null and undefined user variable values to empty strings', () => {
+    const tree = mdxish('`<<nullValue>>|<<undefinedValue>>`', {
+      variables: {
+        user: {
+          nullValue: null,
+          undefinedValue: undefined,
+        },
+        defaults: [],
+      },
+    });
+
+    expect(getCodeText(tree)).toBe('|');
+  });
+
   it('does not double-resolve when a legacy variable value contains an MDX variable pattern', () => {
     const tree = mdxish('`<<payload>>`', {
       variables: {
diff --git a/__tests__/lib/render-mdxish/Variables.test.tsx b/__tests__/lib/render-mdxish/Variables.test.tsx
index 7508db6b2..1c6f23f29 100644
--- a/__tests__/lib/render-mdxish/Variables.test.tsx
+++ b/__tests__/lib/render-mdxish/Variables.test.tsx
@@ -1,10 +1,41 @@
 import '@testing-library/jest-dom';
-import { render } from '@testing-library/react';
+import { render, screen } from '@testing-library/react';
 import React from 'react';
 
 import { mdxish, renderMdxish } from '../../../lib';
 
-describe('render mdxish variables in code', () => {
+describe('render mdxish variables', () => {
+  it.each([
+    {
+      expected: '[{"apiKey":"rdme_123"}]',
+      md: '{user.keys}',
+      name: 'arrays',
+      user: { keys: [{ apiKey: 'rdme_123' }] },
+    },
+    {
+      expected: '{"plan":"enterprise"}',
+      md: '{user.profile}',
+      name: 'objects',
+      user: { profile: { plan: 'enterprise' } },
+    },
+    {
+      expected: '25',
+      md: '{user.limit}',
+      name: 'primitives',
+      user: { limit: 25 },
+    },
+  ])('supports structured user variables: $name', ({ expected, md, user }) => {
+    const variables = {
+      user,
+      defaults: [],
+    };
+    const mod = renderMdxish(mdxish(md, { variables }), { variables });
+
+    render(<mod.default />);
+
+    expect(screen.getByText(expected)).toBeVisible();
+  });
+
   it('resolves legacy and mdx variables in inline code', () => {
     const md = 'Use `<<apiKey>>` and `{user.region}`';
     const variables = {
diff --git a/__tests__/lib/render-mdxish/toc.test.tsx b/__tests__/lib/render-mdxish/toc.test.tsx
index 5a3097385..900621491 100644
--- a/__tests__/lib/render-mdxish/toc.test.tsx
+++ b/__tests__/lib/render-mdxish/toc.test.tsx
@@ -130,6 +130,28 @@ describe('toc transformer', () => {
     expect(screen.findByText('Setup for admins')).toBeDefined();
   });
 
+  it('stringifies structured variables in labels', async () => {
+    const md = `# Keys {user.keys}
+
+## Profile {user.profile} {user.limit}
+`;
+    const variables = {
+      user: {
+        keys: [{ apiKey: 'rdme_123' }],
+        limit: 25,
+        profile: { plan: 'enterprise' },
+      },
+      defaults: [],
+    };
+
+    const { Toc } = renderMdxish(mdxish(md), { variables });
+
+    render(<Toc />);
+
+    expect(await screen.findByText('Keys [{"apiKey":"rdme_123"}]')).toBeDefined();
+    expect(await screen.findByText('Profile {"plan":"enterprise"} 25')).toBeDefined();
+  });
+
   it('keeps adjacent legacy variable values and suffixes together', () => {
     const md = '## Hello <<name>>! Nice';
     const variables = {
diff --git a/__tests__/plugins/toc.test.tsx b/__tests__/plugins/toc.test.tsx
index d9a204133..42ec4cfeb 100644
--- a/__tests__/plugins/toc.test.tsx
+++ b/__tests__/plugins/toc.test.tsx
@@ -229,6 +229,27 @@ export const toc = [
     expect(screen.findByText('Setup for admins')).toBeDefined();
   });
 
+  it('stringifies structured variables in labels', async () => {
+    const md = `# Keys {user.keys}
+
+## Profile {user.profile} {user.limit}`;
+    const variables = {
+      user: {
+        keys: [{ apiKey: 'rdme_123' }],
+        limit: 25,
+        profile: { plan: 'enterprise' },
+      },
+      defaults: [],
+    };
+
+    const { Toc } = run(compile(md), { variables });
+
+    render(<Toc />);
+
+    expect(await screen.findByText('Keys [{"apiKey":"rdme_123"}]')).toBeDefined();
+    expect(await screen.findByText('Profile {"plan":"enterprise"} 25')).toBeDefined();
+  });
+
   it('keeps mixed inline phrasing together', () => {
     const md = '## Hello {user.name}! N*ic*e [day](https://example.com)s';
     const variables = {
diff --git a/__tests__/variables/index.test.tsx b/__tests__/variables/index.test.tsx
index 4b8487f87..e87ec3010 100644
--- a/__tests__/variables/index.test.tsx
+++ b/__tests__/variables/index.test.tsx
@@ -34,4 +34,31 @@ export const Hello = () => <p>{user.name}</p>;
 
     expect(screen.getByText('Owlbert')).toBeVisible();
   });
+
+  it.each([
+    {
+      expected: 'rdme_123',
+      md: '{user.keys[0].apiKey}',
+      name: 'arrays',
+      user: { keys: [{ apiKey: 'rdme_123' }] },
+    },
+    {
+      expected: 'enterprise',
+      md: '{user.profile.plan}',
+      name: 'objects',
+      user: { profile: { plan: 'enterprise' } },
+    },
+    {
+      expected: 'active 25',
+      md: "{user.active ? 'active' : 'inactive'} {user.limit}",
+      name: 'primitives',
+      user: { active: true, limit: 25 },
+    },
+  ])('supports structured user variables: $name', ({ expected, md, user }) => {
+    const Content = execute(md, {}, { variables: { user } });
+
+    render(<Content />);
+
+    expect(screen.getByText(expected)).toBeVisible();
+  });
 });
diff --git a/processor/plugin/toc.ts b/processor/plugin/toc.ts
index 19edce7d4..de0bf591c 100644
--- a/processor/plugin/toc.ts
+++ b/processor/plugin/toc.ts
@@ -16,6 +16,7 @@ import { h } from 'hastscript';
 
 import { mdx, plain } from '../../lib';
 import { STANDARD_HTML_TAGS } from '../../utils/common-html-words';
+import { flattenUserVariables } from '../../utils/user';
 import { hasNamedExport } from '../utils';
 
 const HEADING_TAGS = ['h1', 'h2', 'h3', 'h4', 'h5', 'h6'];
@@ -149,7 +150,7 @@ const getDepth = (el: HastHeading) => {
 const flattenVariables = (variables?: Variables): Record<string, string> => {
   if (!variables) return {};
   return {
-    ...variables.user,
+    ...flattenUserVariables(variables.user),
     ...Object.fromEntries(
       (variables.defaults || []).filter(d => !(d.name in variables.user)).map(d => [d.name, d.default]),
     ),
diff --git a/processor/transform/mdxish/variables-code.ts b/processor/transform/mdxish/variables-code.ts
index 0cc5a6aa0..559cd606a 100644
--- a/processor/transform/mdxish/variables-code.ts
+++ b/processor/transform/mdxish/variables-code.ts
@@ -5,6 +5,8 @@ import type { Plugin } from 'unified';
 import { MDX_VARIABLE_REGEXP, VARIABLE_REGEXP } from '@readme/variable';
 import { visit } from 'unist-util-visit';
 
+import { flattenUserVariables } from '../../../utils/user';
+
 interface Options {
   variables?: Variables;
 }
@@ -18,7 +20,7 @@ function flattenVariables(variables?: Variables): Record<string, string> {
 
   return {
     ...Object.fromEntries((variables.defaults || []).map(d => [d.name, d.default])),
-    ...variables.user,
+    ...flattenUserVariables(variables.user),
   };
 }
 
diff --git a/types.d.ts b/types.d.ts
index 7f7aa4b89..ee0d5ca4c 100644
--- a/types.d.ts
+++ b/types.d.ts
@@ -287,7 +287,7 @@ interface TocList extends Element {
 
 interface Variables {
   defaults: { default: string; name: string }[];
-  user: Record<string, string>;
+  user: Record<string, unknown>;
 }
 
 interface TocListItem extends Element {
diff --git a/utils/user.ts b/utils/user.ts
index db1fc0b74..b9ce912cf 100644
--- a/utils/user.ts
+++ b/utils/user.ts
@@ -5,9 +5,30 @@ interface Default {
 
 export interface Variables {
   defaults: Default[];
-  user: Record<string, string>;
+  user: Record<string, unknown>;
 }
 
+/**
+ * Coerce a user variable value to a string for substitution into markdown text.
+ * Non-string values (arrays, objects, numbers) are stringified via JSON or `String()`
+ * so that `<<var>>` syntax doesn't produce `[object Object]` for structured data like
+ * JWT `keys`.
+ */
+const stringifyVariableValue = (value: unknown): string => {
+  if (typeof value === 'string') return value;
+  if (value == null) return '';
+  if (typeof value === 'object') return JSON.stringify(value) ?? '';
+  return String(value);
+};
+
+/**
+ * Flatten `variables.user` into a string-keyed string-valued record by coercing
+ * each value. Used by markdown substitution paths that need a plain
+ * `Record<string, string>` lookup.
+ */
+export const flattenUserVariables = (user: Record<string, unknown>): Record<string, string> =>
+  Object.fromEntries(Object.entries(user).map(([name, value]) => [name, stringifyVariableValue(value)]));
+
 const User = (variables?: Variables) => {
   const { user = {}, defaults = [] } = variables || {};