diff --git a/ui/src/api/queries/admin/environments.ts b/ui/src/api/queries/admin/environments.ts
new file mode 100644
index 00000000..7e198aa1
--- /dev/null
+++ b/ui/src/api/queries/admin/environments.ts
@@ -0,0 +1,63 @@
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
+import { adminFetch } from './admin-api';
+
+export interface Environment {
+  id: string;
+  slug: string;
+  displayName: string;
+  production: boolean;
+  enabled: boolean;
+  createdAt: string;
+}
+
+export interface CreateEnvironmentRequest {
+  slug: string;
+  displayName: string;
+  production: boolean;
+}
+
+export interface UpdateEnvironmentRequest {
+  displayName: string;
+  production: boolean;
+  enabled: boolean;
+}
+
+export function useEnvironments() {
+  return useQuery({
+    queryKey: ['admin', 'environments'],
+    queryFn: () => adminFetch<Environment[]>('/environments'),
+  });
+}
+
+export function useCreateEnvironment() {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: (req: CreateEnvironmentRequest) =>
+      adminFetch<Environment>('/environments', {
+        method: 'POST',
+        body: JSON.stringify(req),
+      }),
+    onSuccess: () => qc.invalidateQueries({ queryKey: ['admin', 'environments'] }),
+  });
+}
+
+export function useUpdateEnvironment() {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: ({ id, ...req }: UpdateEnvironmentRequest & { id: string }) =>
+      adminFetch<Environment>(`/environments/${id}`, {
+        method: 'PUT',
+        body: JSON.stringify(req),
+      }),
+    onSuccess: () => qc.invalidateQueries({ queryKey: ['admin', 'environments'] }),
+  });
+}
+
+export function useDeleteEnvironment() {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: (id: string) =>
+      adminFetch<void>(`/environments/${id}`, { method: 'DELETE' }),
+    onSuccess: () => qc.invalidateQueries({ queryKey: ['admin', 'environments'] }),
+  });
+}
diff --git a/ui/src/components/sidebar-utils.ts b/ui/src/components/sidebar-utils.ts
index d490f6ec..e2dda212 100644
--- a/ui/src/components/sidebar-utils.ts
+++ b/ui/src/components/sidebar-utils.ts
@@ -98,6 +98,7 @@ export function buildAppTreeNodes(
  */
 export function buildAdminTreeNodes(): SidebarTreeNode[] {
   return [
+    { id: 'admin:environments', label: 'Environments', path: '/admin/environments' },
     { id: 'admin:rbac', label: 'Users & Roles', path: '/admin/rbac' },
     { id: 'admin:audit', label: 'Audit Log', path: '/admin/audit' },
     { id: 'admin:oidc', label: 'OIDC', path: '/admin/oidc' },
diff --git a/ui/src/pages/Admin/EnvironmentsPage.tsx b/ui/src/pages/Admin/EnvironmentsPage.tsx
new file mode 100644
index 00000000..58db7e9a
--- /dev/null
+++ b/ui/src/pages/Admin/EnvironmentsPage.tsx
@@ -0,0 +1,299 @@
+import { useState, useMemo } from 'react';
+import {
+  Avatar,
+  Badge,
+  Button,
+  Input,
+  MonoText,
+  SectionHeader,
+  Tag,
+  Toggle,
+  InlineEdit,
+  ConfirmDialog,
+  SplitPane,
+  EntityList,
+  Spinner,
+  useToast,
+} from '@cameleer/design-system';
+import {
+  useEnvironments,
+  useCreateEnvironment,
+  useUpdateEnvironment,
+  useDeleteEnvironment,
+} from '../../api/queries/admin/environments';
+import type { Environment } from '../../api/queries/admin/environments';
+import styles from './UserManagement.module.css';
+
+export default function EnvironmentsPage() {
+  const { toast } = useToast();
+  const { data: environments = [], isLoading } = useEnvironments();
+
+  const [search, setSearch] = useState('');
+  const [selectedId, setSelectedId] = useState<string | null>(null);
+  const [creating, setCreating] = useState(false);
+  const [deleteTarget, setDeleteTarget] = useState<Environment | null>(null);
+
+  // Create form state
+  const [newSlug, setNewSlug] = useState('');
+  const [newDisplayName, setNewDisplayName] = useState('');
+  const [newProduction, setNewProduction] = useState(false);
+
+  // Mutations
+  const createEnv = useCreateEnvironment();
+  const updateEnv = useUpdateEnvironment();
+  const deleteEnv = useDeleteEnvironment();
+
+  const selected = useMemo(
+    () => environments.find((e) => e.id === selectedId) ?? null,
+    [environments, selectedId],
+  );
+
+  const filtered = useMemo(() => {
+    if (!search) return environments;
+    const q = search.toLowerCase();
+    return environments.filter(
+      (e) =>
+        e.slug.toLowerCase().includes(q) ||
+        e.displayName.toLowerCase().includes(q),
+    );
+  }, [environments, search]);
+
+  const isDefault = selected?.slug === 'default';
+
+  const duplicateSlug =
+    newSlug.trim() !== '' &&
+    environments.some((e) => e.slug.toLowerCase() === newSlug.trim().toLowerCase());
+
+  async function handleCreate() {
+    if (!newSlug.trim() || !newDisplayName.trim()) return;
+    try {
+      await createEnv.mutateAsync({
+        slug: newSlug.trim(),
+        displayName: newDisplayName.trim(),
+        production: newProduction,
+      });
+      toast({ title: 'Environment created', description: newSlug.trim(), variant: 'success' });
+      setCreating(false);
+      setNewSlug('');
+      setNewDisplayName('');
+      setNewProduction(false);
+    } catch {
+      toast({ title: 'Failed to create environment', variant: 'error', duration: 86_400_000 });
+    }
+  }
+
+  async function handleDelete() {
+    if (!deleteTarget) return;
+    try {
+      await deleteEnv.mutateAsync(deleteTarget.id);
+      toast({ title: 'Environment deleted', description: deleteTarget.slug, variant: 'warning' });
+      if (selectedId === deleteTarget.id) setSelectedId(null);
+      setDeleteTarget(null);
+    } catch {
+      toast({ title: 'Failed to delete environment', variant: 'error', duration: 86_400_000 });
+      setDeleteTarget(null);
+    }
+  }
+
+  async function handleRename(newName: string) {
+    if (!selected) return;
+    try {
+      await updateEnv.mutateAsync({
+        id: selected.id,
+        displayName: newName,
+        production: selected.production,
+        enabled: selected.enabled,
+      });
+      toast({ title: 'Environment renamed', variant: 'success' });
+    } catch {
+      toast({ title: 'Failed to rename', variant: 'error', duration: 86_400_000 });
+    }
+  }
+
+  async function handleToggleProduction(value: boolean) {
+    if (!selected) return;
+    try {
+      await updateEnv.mutateAsync({
+        id: selected.id,
+        displayName: selected.displayName,
+        production: value,
+        enabled: selected.enabled,
+      });
+      toast({ title: value ? 'Marked as production' : 'Marked as non-production', variant: 'success' });
+    } catch {
+      toast({ title: 'Failed to update', variant: 'error', duration: 86_400_000 });
+    }
+  }
+
+  async function handleToggleEnabled(value: boolean) {
+    if (!selected) return;
+    try {
+      await updateEnv.mutateAsync({
+        id: selected.id,
+        displayName: selected.displayName,
+        production: selected.production,
+        enabled: value,
+      });
+      toast({ title: value ? 'Environment enabled' : 'Environment disabled', variant: 'success' });
+    } catch {
+      toast({ title: 'Failed to update', variant: 'error', duration: 86_400_000 });
+    }
+  }
+
+  if (isLoading) return <Spinner size="md" />;
+
+  return (
+    <>
+      <SplitPane
+        list={
+          <>
+            {creating && (
+              <div className={styles.createForm}>
+                <Input
+                  placeholder="Slug (e.g. staging) *"
+                  value={newSlug}
+                  onChange={(e) => setNewSlug(e.target.value)}
+                />
+                {duplicateSlug && (
+                  <span className={styles.errorText}>Slug already exists</span>
+                )}
+                <Input
+                  placeholder="Display name *"
+                  value={newDisplayName}
+                  onChange={(e) => setNewDisplayName(e.target.value)}
+                />
+                <label className={styles.securityRow}>
+                  <Toggle checked={newProduction} onChange={() => setNewProduction(!newProduction)} />
+                  Production environment
+                </label>
+                <div className={styles.createFormActions}>
+                  <Button size="sm" variant="ghost" onClick={() => setCreating(false)}>
+                    Cancel
+                  </Button>
+                  <Button
+                    size="sm"
+                    variant="primary"
+                    onClick={handleCreate}
+                    loading={createEnv.isPending}
+                    disabled={!newSlug.trim() || !newDisplayName.trim() || duplicateSlug}
+                  >
+                    Create
+                  </Button>
+                </div>
+              </div>
+            )}
+
+            <EntityList
+              items={filtered}
+              renderItem={(env) => (
+                <>
+                  <Avatar name={env.displayName} size="sm" />
+                  <div className={styles.entityInfo}>
+                    <div className={styles.entityName}>{env.displayName}</div>
+                    <div className={styles.entityMeta}>
+                      {env.slug}
+                    </div>
+                    <div className={styles.entityTags}>
+                      {env.production && <Badge label="PROD" color="error" />}
+                      {!env.production && <Badge label="NON-PROD" color="auto" />}
+                      {!env.enabled && <Badge label="DISABLED" color="warning" />}
+                    </div>
+                  </div>
+                </>
+              )}
+              getItemId={(env) => env.id}
+              selectedId={selectedId ?? undefined}
+              onSelect={setSelectedId}
+              searchPlaceholder="Search environments..."
+              onSearch={setSearch}
+              addLabel="+ Add environment"
+              onAdd={() => setCreating(true)}
+              emptyMessage="No environments match your search"
+            />
+          </>
+        }
+        detail={
+          selected ? (
+            <>
+              <div className={styles.detailHeader}>
+                <Avatar name={selected.displayName} size="lg" />
+                <div className={styles.detailHeaderInfo}>
+                  <div className={styles.detailName}>
+                    {isDefault ? (
+                      selected.displayName
+                    ) : (
+                      <InlineEdit value={selected.displayName} onSave={handleRename} />
+                    )}
+                  </div>
+                  <div className={styles.detailEmail}>
+                    {selected.slug}
+                    {isDefault && ' (built-in)'}
+                  </div>
+                </div>
+                <Button
+                  size="sm"
+                  variant="danger"
+                  onClick={() => setDeleteTarget(selected)}
+                  disabled={isDefault}
+                >
+                  Delete
+                </Button>
+              </div>
+
+              <div className={styles.metaGrid}>
+                <span className={styles.metaLabel}>ID</span>
+                <MonoText size="xs">{selected.id}</MonoText>
+                <span className={styles.metaLabel}>Slug</span>
+                <span className={styles.metaValue}>{selected.slug}</span>
+                <span className={styles.metaLabel}>Created</span>
+                <span className={styles.metaValue}>
+                  {new Date(selected.createdAt).toLocaleDateString()}
+                </span>
+              </div>
+
+              <SectionHeader>Configuration</SectionHeader>
+              <div className={styles.securitySection}>
+                <div className={styles.securityRow}>
+                  <Toggle checked={selected.production} onChange={() => handleToggleProduction(!selected.production)} />
+                  <span>Production environment</span>
+                  {selected.production ? (
+                    <Tag label="Dedicated resources" color="error" />
+                  ) : (
+                    <Tag label="Shared resources" color="auto" />
+                  )}
+                </div>
+              </div>
+
+              <SectionHeader>Status</SectionHeader>
+              <div className={styles.securitySection}>
+                <div className={styles.securityRow}>
+                  <Toggle checked={selected.enabled} onChange={() => handleToggleEnabled(!selected.enabled)} />
+                  <span>{selected.enabled ? 'Enabled' : 'Disabled'}</span>
+                  {!selected.enabled && (
+                    <Tag label="No new deployments" color="warning" />
+                  )}
+                </div>
+                {!selected.enabled && (
+                  <p className={styles.inheritedNote}>
+                    Disabled environments do not allow new deployments. Active
+                    deployments can only be started, stopped, or deleted.
+                  </p>
+                )}
+              </div>
+            </>
+          ) : null
+        }
+        emptyMessage="Select an environment to view details"
+      />
+
+      <ConfirmDialog
+        open={deleteTarget !== null}
+        onClose={() => setDeleteTarget(null)}
+        onConfirm={handleDelete}
+        message={`Delete environment "${deleteTarget?.displayName}"? All apps and deployments in this environment will be removed. This cannot be undone.`}
+        confirmText={deleteTarget?.slug ?? ''}
+        loading={deleteEnv.isPending}
+      />
+    </>
+  );
+}
diff --git a/ui/src/router.tsx b/ui/src/router.tsx
index fc09fb37..7cceaeb9 100644
--- a/ui/src/router.tsx
+++ b/ui/src/router.tsx
@@ -17,6 +17,7 @@ const AuditLogPage = lazy(() => import('./pages/Admin/AuditLogPage'));
 const OidcConfigPage = lazy(() => import('./pages/Admin/OidcConfigPage'));
 const DatabaseAdminPage = lazy(() => import('./pages/Admin/DatabaseAdminPage'));
 const ClickHouseAdminPage = lazy(() => import('./pages/Admin/ClickHouseAdminPage'));
+const EnvironmentsPage = lazy(() => import('./pages/Admin/EnvironmentsPage'));
 const AppConfigPage = lazy(() => import('./pages/Admin/AppConfigPage'));
 const LogsPage = lazy(() => import('./pages/LogsTab/LogsPage'));
 const SwaggerPage = lazy(() => import('./pages/Swagger/SwaggerPage'));
@@ -81,6 +82,7 @@ export const router = createBrowserRouter([
                 { path: 'oidc', element: <SuspenseWrapper><OidcConfigPage /></SuspenseWrapper> },
                 { path: 'database', element: <SuspenseWrapper><DatabaseAdminPage /></SuspenseWrapper> },
                 { path: 'clickhouse', element: <SuspenseWrapper><ClickHouseAdminPage /></SuspenseWrapper> },
+                { path: 'environments', element: <SuspenseWrapper><EnvironmentsPage /></SuspenseWrapper> },
               ],
             }],
           },