diff --git a/src/Map/cesiumIonDetection.test.ts b/src/Map/cesiumIonDetection.test.ts
new file mode 100644
index 0000000..8c6aaa0
--- /dev/null
+++ b/src/Map/cesiumIonDetection.test.ts
@@ -0,0 +1,245 @@
+import { describe, expect, test } from "vitest";
+
+import { computeHasCesiumIonAsset } from "./cesiumIonDetection";
+
+const makeSimple = (data?: object) => ({
+  id: "layer1",
+  type: "simple" as const,
+  ...(data ? { data } : {}),
+});
+
+const makeGroup = (children: object[]) => ({
+  id: "group1",
+  type: "group" as const,
+  children,
+});
+
+describe("computeHasCesiumIonAsset", () => {
+  describe("tiles", () => {
+    test("returns false when no tiles", () => {
+      expect(computeHasCesiumIonAsset({ tiles: [] })).toBe(false);
+    });
+
+    test("returns true for cesium_ion tile type", () => {
+      expect(
+        computeHasCesiumIonAsset({ tiles: [{ id: "", type: "cesium_ion" }] }),
+      ).toBe(true);
+    });
+
+    test("returns true for cesium_ion_default tile type", () => {
+      expect(
+        computeHasCesiumIonAsset({
+          tiles: [{ id: "", type: "cesium_ion_default" }],
+        }),
+      ).toBe(true);
+    });
+
+    test("returns true for legacy tile types", () => {
+      for (const type of [
+        "default",
+        "default_road",
+        "default_label",
+        "black_marble",
+      ]) {
+        expect(computeHasCesiumIonAsset({ tiles: [{ id: "", type }] })).toBe(
+          true,
+        );
+      }
+    });
+
+    test("returns false for non-ion tile type", () => {
+      expect(
+        computeHasCesiumIonAsset({
+          tiles: [{ id: "", type: "open_street_map" }],
+        }),
+      ).toBe(false);
+    });
+  });
+
+  describe("terrain", () => {
+    test("returns true for cesium terrain type when enabled", () => {
+      expect(
+        computeHasCesiumIonAsset({
+          terrain: { enabled: true, type: "cesium" },
+        }),
+      ).toBe(true);
+    });
+
+    test("returns true for cesiumion terrain type when enabled", () => {
+      expect(
+        computeHasCesiumIonAsset({
+          terrain: { enabled: true, type: "cesiumion" },
+        }),
+      ).toBe(true);
+    });
+
+    test("returns false for cesium terrain when disabled", () => {
+      expect(
+        computeHasCesiumIonAsset({
+          terrain: { enabled: false, type: "cesium" },
+        }),
+      ).toBe(false);
+    });
+
+    test("returns true for ion terrain URL", () => {
+      expect(
+        computeHasCesiumIonAsset({
+          terrain: { enabled: true, type: "url" },
+          assets: {
+            cesium: {
+              terrain: {
+                ionUrl: "https://assets.ion.cesium.com/1/tileset.json",
+              },
+            },
+          },
+        } as any),
+      ).toBe(true);
+    });
+
+    test("returns false for non-ion terrain URL", () => {
+      expect(
+        computeHasCesiumIonAsset({
+          terrain: { enabled: true, type: "url" },
+          assets: {
+            cesium: { terrain: { ionUrl: "https://example.com/terrain" } },
+          },
+        } as any),
+      ).toBe(false);
+    });
+  });
+
+  describe("layers", () => {
+    test("returns true for osm-buildings layer", () => {
+      expect(
+        computeHasCesiumIonAsset(undefined, [
+          makeSimple({ type: "osm-buildings" }),
+        ] as any),
+      ).toBe(true);
+    });
+
+    test("returns true for google-photorealistic with cesium-ion provider", () => {
+      expect(
+        computeHasCesiumIonAsset(undefined, [
+          makeSimple({ type: "google-photorealistic", provider: "cesium-ion" }),
+        ] as any),
+      ).toBe(true);
+    });
+
+    test("returns false for google-photorealistic with reearth provider", () => {
+      expect(
+        computeHasCesiumIonAsset(undefined, [
+          makeSimple({ type: "google-photorealistic", provider: "reearth" }),
+        ] as any),
+      ).toBe(false);
+    });
+
+    test("returns false for google-photorealistic with no provider (google API path)", () => {
+      expect(
+        computeHasCesiumIonAsset(undefined, [
+          makeSimple({ type: "google-photorealistic" }),
+        ] as any),
+      ).toBe(false);
+    });
+
+    test("returns true for layer with ion URL", () => {
+      expect(
+        computeHasCesiumIonAsset(undefined, [
+          makeSimple({
+            type: "3dtiles",
+            url: "https://assets.ion.cesium.com/123/tileset.json",
+          }),
+        ] as any),
+      ).toBe(true);
+    });
+
+    test("returns true for any layer type with ion URL", () => {
+      expect(
+        computeHasCesiumIonAsset(undefined, [
+          makeSimple({
+            type: "geojson",
+            url: "https://assets.ion.cesium.com/456/data.json",
+          }),
+        ] as any),
+      ).toBe(true);
+    });
+
+    test("returns false for layer with non-ion URL", () => {
+      expect(
+        computeHasCesiumIonAsset(undefined, [
+          makeSimple({
+            type: "3dtiles",
+            url: "https://example.com/tileset.json",
+          }),
+        ] as any),
+      ).toBe(false);
+    });
+
+    test("returns false for layer with no data", () => {
+      expect(computeHasCesiumIonAsset(undefined, [makeSimple()] as any)).toBe(
+        false,
+      );
+    });
+  });
+
+  describe("layer groups (recursion)", () => {
+    test("returns true when nested layer uses ion", () => {
+      const group = makeGroup([makeSimple({ type: "osm-buildings" })]);
+      expect(computeHasCesiumIonAsset(undefined, [group] as any)).toBe(true);
+    });
+
+    test("returns false when nested layer does not use ion", () => {
+      const group = makeGroup([
+        makeSimple({ type: "geojson", url: "https://example.com/data.json" }),
+      ]);
+      expect(computeHasCesiumIonAsset(undefined, [group] as any)).toBe(false);
+    });
+
+    test("returns true when deeply nested layer uses ion", () => {
+      const inner = makeGroup([makeSimple({ type: "osm-buildings" })]);
+      const outer = makeGroup([inner]);
+      expect(computeHasCesiumIonAsset(undefined, [outer] as any)).toBe(true);
+    });
+  });
+
+  describe("combined", () => {
+    test("returns false when nothing uses ion", () => {
+      expect(
+        computeHasCesiumIonAsset(
+          {
+            tiles: [{ id: "", type: "open_street_map" }],
+            terrain: { enabled: false, type: "cesium" },
+          },
+          [
+            makeSimple({
+              type: "geojson",
+              url: "https://example.com/data.json",
+            }),
+          ] as any,
+        ),
+      ).toBe(false);
+    });
+
+    test("returns true when only tile uses ion", () => {
+      expect(
+        computeHasCesiumIonAsset({ tiles: [{ id: "", type: "default" }] }, [
+          makeSimple({ type: "geojson" }),
+        ] as any),
+      ).toBe(true);
+    });
+
+    test("returns true when only terrain uses ion", () => {
+      expect(
+        computeHasCesiumIonAsset(
+          { terrain: { enabled: true, type: "cesium" } },
+          [makeSimple({ type: "geojson" })] as any,
+        ),
+      ).toBe(true);
+    });
+
+    test("returns undefined-safe (no property, no layers)", () => {
+      expect(computeHasCesiumIonAsset()).toBe(false);
+      expect(computeHasCesiumIonAsset(undefined, undefined)).toBe(false);
+      expect(computeHasCesiumIonAsset(undefined, [])).toBe(false);
+    });
+  });
+});
diff --git a/src/Map/cesiumIonDetection.ts b/src/Map/cesiumIonDetection.ts
new file mode 100644
index 0000000..ad3290f
--- /dev/null
+++ b/src/Map/cesiumIonDetection.ts
@@ -0,0 +1,55 @@
+import type { Layer, LayerSimple } from "../mantle";
+
+import type { TileProperty, ViewerProperty } from "./types/viewerProperty";
+
+const CESIUM_ION_URL_PATTERN = "ion.cesium.com";
+const CESIUM_ION_LEGACY_TILE_TYPES = new Set([
+  "default",
+  "default_road",
+  "default_label",
+  "black_marble",
+]);
+
+function isIonUrl(url?: string | null): boolean {
+  return !!url && url.includes(CESIUM_ION_URL_PATTERN);
+}
+
+function tileUsesIon(tile: TileProperty): boolean {
+  if (!tile.type) return false;
+  if (tile.type.startsWith("cesium_ion")) return true;
+  if (CESIUM_ION_LEGACY_TILE_TYPES.has(tile.type)) return true;
+  return false;
+}
+
+function terrainUsesIon(property?: ViewerProperty): boolean {
+  const terrain = property?.terrain;
+  if (!terrain?.enabled) return false;
+  if (terrain.type === "cesium" || terrain.type === "cesiumion") return true;
+  if (isIonUrl(property?.assets?.cesium?.terrain?.ionUrl)) return true;
+  return false;
+}
+
+function layerUsesIon(layer: LayerSimple): boolean {
+  const data = layer.data;
+  if (!data) return false;
+  if (data.type === "osm-buildings") return true;
+  if (data.type === "google-photorealistic") {
+    return data.provider === "cesium-ion";
+  }
+  if (isIonUrl(data.url)) return true;
+  return false;
+}
+
+function anyLayerUsesIon(layer: Layer): boolean {
+  if (layer.type === "group") {
+    return layer.children.some(anyLayerUsesIon);
+  }
+  return layerUsesIon(layer);
+}
+
+export function computeHasCesiumIonAsset(property?: ViewerProperty, layers?: Layer[]): boolean {
+  if (property?.tiles?.some(tileUsesIon)) return true;
+  if (terrainUsesIon(property)) return true;
+  if (layers?.some(anyLayerUsesIon)) return true;
+  return false;
+}
diff --git a/src/Map/index.tsx b/src/Map/index.tsx
index 1325257..351a852 100644
--- a/src/Map/index.tsx
+++ b/src/Map/index.tsx
@@ -2,6 +2,7 @@ import { forwardRef, useMemo, type Ref, type JSX } from "react";
 
 import { INTERACTION_MODES } from "../shared/interactionMode";
 
+import { computeHasCesiumIonAsset } from "./cesiumIonDetection";
 import Geoid from "./Geoid";
 import useHooks, { MapRef } from "./hooks";
 import Layers, { type Props as LayersProps } from "./Layers";
@@ -44,7 +45,10 @@ export type Props = {
   | "selectedLayerId"
   | "viewerProperty"
 > &
-  Omit<EngineProps, "onLayerSelect" | "layerSelectionReason" | "selectedLayerId"> &
+  Omit<
+    EngineProps,
+    "onLayerSelect" | "layerSelectionReason" | "selectedLayerId" | "hasCesiumIonAsset"
+  > &
   Omit<SketchProps, "layersRef" | "engineRef" | "SketchComponent">;
 
 function MapFn(
@@ -102,6 +106,11 @@ function MapFn(
     onAPIReady,
   });
 
+  const hasCesiumIonAsset = useMemo(
+    () => computeHasCesiumIonAsset(props.property, layers),
+    [props.property, layers],
+  );
+
   const selectedLayerIds = useMemo(
     () => ({
       layerId: selectedLayer.layerId,
@@ -125,7 +134,8 @@ function MapFn(
       onLayerSelect={handleEngineLayerSelect}
       featureFlags={featureFlags}
       onMount={handleEngineMount}
-      {...props}>
+      {...props}
+      hasCesiumIonAsset={hasCesiumIonAsset}>
       <Layers
         ref={layersRef}
         engineRef={engineRef}
diff --git a/src/Map/types/index.ts b/src/Map/types/index.ts
index 00d448b..9eed905 100644
--- a/src/Map/types/index.ts
+++ b/src/Map/types/index.ts
@@ -241,6 +241,7 @@ export type EngineProps = {
   meta?: Record<string, unknown>;
   customProvider?: CustomProviderConfig;
   displayCredits?: boolean;
+  hasCesiumIonAsset?: boolean;
   layersRef?: RefObject<LayersRef | null>;
   requestingRenderMode?: MutableRefObject<RequestingRenderMode>;
   timelineManagerRef?: TimelineManagerRef;
diff --git a/src/engines/Cesium/common.ts b/src/engines/Cesium/common.ts
index 67f26ea..d37748e 100644
--- a/src/engines/Cesium/common.ts
+++ b/src/engines/Cesium/common.ts
@@ -905,7 +905,7 @@ export function getExtrudedHeight(
   return;
 }
 
-export function getCredits(viewer: Viewer) {
+export function getCredits(viewer: Viewer, hasCesiumIonAsset?: boolean) {
   if (!viewer) return emptyCredites;
   const creditDisplay = viewer.creditDisplay as
     | (CreditDisplay & {
@@ -924,7 +924,14 @@ export function getCredits(viewer: Viewer) {
 
   const credits: Credits = {
     engine: {
-      cesium: cesiumCredits?.html ? { html: cesiumCredits.html } : undefined,
+      // Only include Cesium-ion credit when Ion assets are actually in use.
+      // hasCesiumIonAsset === false means explicitly no Ion assets; undefined preserves existing behavior.
+      cesium:
+        hasCesiumIonAsset === false
+          ? undefined
+          : cesiumCredits?.html
+            ? { html: cesiumCredits.html }
+            : undefined,
     },
     lightbox: Array.from(lightboxCredits?._array ?? []).map(c => ({
       html: c?.credit?.html,
diff --git a/src/engines/Cesium/hooks.ts b/src/engines/Cesium/hooks.ts
index 1820148..c66f3d0 100644
--- a/src/engines/Cesium/hooks.ts
+++ b/src/engines/Cesium/hooks.ts
@@ -92,6 +92,7 @@ export default ({
   onCameraChange,
   onMount,
   onCreditsUpdate,
+  hasCesiumIonAsset,
 }: {
   ref: React.ForwardedRef<EngineRef>;
   property?: ViewerProperty;
@@ -133,6 +134,7 @@ export default ({
   onCameraChange?: (camera: Camera) => void;
   onMount?: () => void;
   onCreditsUpdate?: (credits: Credits) => void;
+  hasCesiumIonAsset?: boolean;
 }) => {
   const cesium = useRef<CesiumComponentRef<CesiumViewer>>(null);
 
@@ -141,8 +143,11 @@ export default ({
       ? meta.cesiumIonAccessToken
       : undefined;
 
+  const hasCesiumIonAssetRef = useRef(hasCesiumIonAsset);
+  hasCesiumIonAssetRef.current = hasCesiumIonAsset;
+
   // expose ref
-  const engineAPI = useEngineRef(ref, cesium);
+  const engineAPI = useEngineRef(ref, cesium, hasCesiumIonAssetRef);
 
   const layerSelectWithRectEventHandlers = useLayerSelectWithRect({
     cesium,
@@ -667,7 +672,7 @@ export default ({
       if (!onCreditsUpdateRef.current) return;
       const viewer = cesium.current?.cesiumElement;
       if (!viewer || viewer.isDestroyed()) return;
-      const credits = getCredits(viewer);
+      const credits = getCredits(viewer, hasCesiumIonAssetRef.current);
       onCreditsUpdateRef.current(credits);
     }, 3000);
   }, []);
diff --git a/src/engines/Cesium/hooks/useEngineRef.ts b/src/engines/Cesium/hooks/useEngineRef.ts
index 819f920..3dd4d22 100644
--- a/src/engines/Cesium/hooks/useEngineRef.ts
+++ b/src/engines/Cesium/hooks/useEngineRef.ts
@@ -51,6 +51,7 @@ import {
 export default function useEngineRef(
   ref: Ref<EngineRef>,
   cesium: RefObject<CesiumComponentRef<Cesium.Viewer> | null>,
+  hasCesiumIonAssetRef?: RefObject<boolean | undefined>,
 ): EngineRef {
   const cancelCameraFlight = useRef<() => void>(undefined);
   const mouseEventCallbacks = useRef<MouseEventCallbacks>({
@@ -983,10 +984,10 @@ export default function useEngineRef(
       getCredits: () => {
         const viewer = cesium.current?.cesiumElement;
         if (!viewer || viewer.isDestroyed()) return;
-        return getCredits(viewer);
+        return getCredits(viewer, hasCesiumIonAssetRef?.current);
       },
     };
-  }, [cesium]);
+  }, [cesium, hasCesiumIonAssetRef]);
 
   useImperativeHandle(ref, () => e, [e]);
 
diff --git a/src/engines/Cesium/index.tsx b/src/engines/Cesium/index.tsx
index 6a920e1..022cfec 100644
--- a/src/engines/Cesium/index.tsx
+++ b/src/engines/Cesium/index.tsx
@@ -49,6 +49,7 @@ const Cesium: React.ForwardRefRenderFunction<EngineRef, EngineProps> = (
     meta,
     customProvider,
     displayCredits,
+    hasCesiumIonAsset,
     layersRef,
     featureFlags,
     requestingRenderMode,
@@ -119,6 +120,7 @@ const Cesium: React.ForwardRefRenderFunction<EngineRef, EngineProps> = (
     onCameraChange,
     onMount,
     onCreditsUpdate,
+    hasCesiumIonAsset,
   });
 
   const verticalExaggeration = property?.terrain?.enabled