diff --git a/ui/src/pages/Admin/RbacPage.tsx b/ui/src/pages/Admin/RbacPage.tsx
index b00f28a5..f5e7a147 100644
--- a/ui/src/pages/Admin/RbacPage.tsx
+++ b/ui/src/pages/Admin/RbacPage.tsx
@@ -2,12 +2,11 @@ import { useState } from 'react';
 import { StatCard, Tabs } from '@cameleer/design-system';
 import { useRbacStats } from '../../api/queries/admin/rbac';
 import styles from './UserManagement.module.css';
+import GroupsTab from './GroupsTab';
+import RolesTab from './RolesTab';
 
-// Lazy imports for tab components (will be created in tasks 17-19)
-// For now, use placeholder components so the page compiles
+// Placeholder component for Users tab (task 17)
 const UsersTab = () => <div>Users tab — coming soon</div>;
-const GroupsTab = () => <div>Groups tab — coming soon</div>;
-const RolesTab = () => <div>Roles tab — coming soon</div>;
 
 export default function RbacPage() {
   const { data: stats } = useRbacStats();
diff --git a/ui/src/pages/Admin/RolesTab.tsx b/ui/src/pages/Admin/RolesTab.tsx
new file mode 100644
index 00000000..9202c214
--- /dev/null
+++ b/ui/src/pages/Admin/RolesTab.tsx
@@ -0,0 +1,305 @@
+import { useState } from 'react';
+import {
+  Avatar,
+  Badge,
+  Button,
+  ConfirmDialog,
+  Input,
+  MonoText,
+  Spinner,
+  Tag,
+  useToast,
+} from '@cameleer/design-system';
+import {
+  useRoles,
+  useRole,
+  useCreateRole,
+  useDeleteRole,
+} from '../../api/queries/admin/rbac';
+import type { RoleDetail } from '../../api/queries/admin/rbac';
+import styles from './UserManagement.module.css';
+
+export default function RolesTab() {
+  const { data: roles, isLoading } = useRoles();
+  const [selectedId, setSelectedId] = useState<string | null>(null);
+  const [search, setSearch] = useState('');
+  const [showCreate, setShowCreate] = useState(false);
+  const [newName, setNewName] = useState('');
+  const [newDescription, setNewDescription] = useState('');
+  const [confirmDelete, setConfirmDelete] = useState(false);
+
+  const { data: detail, isLoading: detailLoading } = useRole(selectedId);
+  const createRole = useCreateRole();
+  const deleteRole = useDeleteRole();
+  const { toast } = useToast();
+
+  const filtered = (roles ?? []).filter((r) =>
+    r.name.toLowerCase().includes(search.toLowerCase()),
+  );
+
+  function handleCreate() {
+    if (!newName.trim()) return;
+    createRole.mutate(
+      { name: newName.trim(), description: newDescription.trim() || undefined },
+      {
+        onSuccess: () => {
+          toast({ title: 'Role created', variant: 'success' });
+          setShowCreate(false);
+          setNewName('');
+          setNewDescription('');
+        },
+        onError: () => {
+          toast({ title: 'Failed to create role', variant: 'error' });
+        },
+      },
+    );
+  }
+
+  function handleDelete() {
+    if (!selectedId) return;
+    deleteRole.mutate(selectedId, {
+      onSuccess: () => {
+        toast({ title: 'Role deleted', variant: 'success' });
+        setSelectedId(null);
+        setConfirmDelete(false);
+      },
+      onError: () => {
+        toast({ title: 'Failed to delete role', variant: 'error' });
+        setConfirmDelete(false);
+      },
+    });
+  }
+
+  return (
+    <div className={styles.splitPane}>
+      {/* Left pane — list */}
+      <div className={styles.listPane}>
+        <div className={styles.listHeader}>
+          <Input
+            placeholder="Search roles…"
+            value={search}
+            onChange={(e) => setSearch(e.target.value)}
+          />
+          <Button
+            variant="secondary"
+            size="sm"
+            onClick={() => setShowCreate((v) => !v)}
+          >
+            + Add Role
+          </Button>
+        </div>
+
+        {showCreate && (
+          <div className={styles.createForm}>
+            <Input
+              placeholder="Role name (e.g. EDITOR)"
+              value={newName}
+              onChange={(e) => setNewName(e.target.value.toUpperCase())}
+              style={{ marginBottom: 8 }}
+            />
+            <Input
+              placeholder="Description (optional)"
+              value={newDescription}
+              onChange={(e) => setNewDescription(e.target.value)}
+            />
+            <div className={styles.createFormActions}>
+              <Button
+                variant="ghost"
+                size="sm"
+                onClick={() => {
+                  setShowCreate(false);
+                  setNewName('');
+                  setNewDescription('');
+                }}
+              >
+                Cancel
+              </Button>
+              <Button
+                variant="primary"
+                size="sm"
+                loading={createRole.isPending}
+                disabled={!newName.trim()}
+                onClick={handleCreate}
+              >
+                Create
+              </Button>
+            </div>
+          </div>
+        )}
+
+        {isLoading ? (
+          <Spinner />
+        ) : (
+          <div className={styles.entityList} role="listbox">
+            {filtered.map((role) => {
+              const assignmentCount =
+                (role.assignedGroups?.length ?? 0) + (role.directUsers?.length ?? 0);
+              return (
+                <div
+                  key={role.id}
+                  className={
+                    styles.entityItem +
+                    (selectedId === role.id ? ' ' + styles.entityItemSelected : '')
+                  }
+                  role="option"
+                  aria-selected={selectedId === role.id}
+                  onClick={() => setSelectedId(role.id)}
+                >
+                  <Avatar name={role.name} size="sm" />
+                  <div className={styles.entityInfo}>
+                    <div className={styles.entityName}>
+                      {role.name}
+                      {role.system && <Badge label="system" variant="outlined" />}
+                    </div>
+                    <div className={styles.entityMeta}>
+                      {role.description || '—'} · {assignmentCount} assignment
+                      {assignmentCount !== 1 ? 's' : ''}
+                    </div>
+                    {((role.assignedGroups?.length ?? 0) > 0 ||
+                      (role.directUsers?.length ?? 0) > 0) && (
+                      <div className={styles.entityTags}>
+                        {(role.assignedGroups ?? []).map((g) => (
+                          <Tag key={g.id} label={g.name} color="success" />
+                        ))}
+                        {(role.directUsers ?? []).map((u) => (
+                          <Tag key={u.userId} label={u.displayName} />
+                        ))}
+                      </div>
+                    )}
+                  </div>
+                </div>
+              );
+            })}
+          </div>
+        )}
+      </div>
+
+      {/* Right pane — detail */}
+      <div className={styles.detailPane}>
+        {!selectedId ? (
+          <div className={styles.emptyDetail}>Select a role to view details</div>
+        ) : detailLoading || !detail ? (
+          <Spinner />
+        ) : (
+          <RoleDetailPanel
+            role={detail}
+            onDeleteRequest={() => setConfirmDelete(true)}
+          />
+        )}
+      </div>
+
+      {detail && (
+        <ConfirmDialog
+          open={confirmDelete}
+          onClose={() => setConfirmDelete(false)}
+          onConfirm={handleDelete}
+          title="Delete role"
+          message={`Delete role "${detail.name}"? This cannot be undone.`}
+          confirmText={detail.name}
+          confirmLabel="Delete"
+          variant="danger"
+          loading={deleteRole.isPending}
+        />
+      )}
+    </div>
+  );
+}
+
+// ── Detail panel ──────────────────────────────────────────────────────────────
+
+interface RoleDetailPanelProps {
+  role: RoleDetail;
+  onDeleteRequest: () => void;
+}
+
+function RoleDetailPanel({ role, onDeleteRequest }: RoleDetailPanelProps) {
+  // Build a set of directly-assigned user IDs for distinguishing inherited principals
+  const directUserIds = new Set((role.directUsers ?? []).map((u) => u.userId));
+
+  return (
+    <div>
+      {/* Header */}
+      <div className={styles.detailHeader}>
+        <Avatar name={role.name} size="md" />
+        <div style={{ flex: 1 }}>
+          <div style={{ fontWeight: 700, fontSize: 16 }}>{role.name}</div>
+          {role.description && (
+            <div style={{ fontSize: 12, color: 'var(--text-muted)', marginTop: 2 }}>
+              {role.description}
+            </div>
+          )}
+        </div>
+        <Button
+          variant="danger"
+          size="sm"
+          disabled={role.system}
+          onClick={onDeleteRequest}
+        >
+          Delete
+        </Button>
+      </div>
+
+      {/* Metadata */}
+      <div className={styles.metaGrid}>
+        <span className={styles.metaLabel}>ID</span>
+        <MonoText size="xs">{role.id}</MonoText>
+
+        <span className={styles.metaLabel}>Scope</span>
+        <span>{role.scope || '—'}</span>
+
+        <span className={styles.metaLabel}>Type</span>
+        <span>{role.system ? 'System role (read-only)' : 'Custom role'}</span>
+      </div>
+
+      {/* Assigned to groups */}
+      <div className={styles.sectionTitle}>Assigned to groups</div>
+      <div className={styles.sectionTags}>
+        {(role.assignedGroups ?? []).length === 0 ? (
+          <span style={{ fontSize: 12, color: 'var(--text-muted)' }}>None</span>
+        ) : (
+          (role.assignedGroups ?? []).map((g) => (
+            <Tag key={g.id} label={g.name} color="success" />
+          ))
+        )}
+      </div>
+
+      {/* Assigned to users (direct) */}
+      <div className={styles.sectionTitle}>Assigned to users (direct)</div>
+      <div className={styles.sectionTags}>
+        {(role.directUsers ?? []).length === 0 ? (
+          <span style={{ fontSize: 12, color: 'var(--text-muted)' }}>None</span>
+        ) : (
+          (role.directUsers ?? []).map((u) => (
+            <Tag key={u.userId} label={u.displayName} />
+          ))
+        )}
+      </div>
+
+      {/* Effective principals */}
+      <div className={styles.sectionTitle}>Effective principals</div>
+      <div className={styles.sectionTags}>
+        {(role.effectivePrincipals ?? []).length === 0 ? (
+          <span style={{ fontSize: 12, color: 'var(--text-muted)' }}>None</span>
+        ) : (
+          (role.effectivePrincipals ?? []).map((u) => {
+            const isDirect = directUserIds.has(u.userId);
+            return isDirect ? (
+              <Badge key={u.userId} label={u.displayName} variant="filled" />
+            ) : (
+              <Badge
+                key={u.userId}
+                label={`↑ ${u.displayName}`}
+                variant="dashed"
+              />
+            );
+          })
+        )}
+      </div>
+      {(role.effectivePrincipals ?? []).some((u) => !directUserIds.has(u.userId)) && (
+        <div className={styles.inheritedNote}>
+          Dashed entries inherit this role through group membership
+        </div>
+      )}
+    </div>
+  );
+}