diff --git a/packages/core/changelog/@unreleased/pr-7137.v2.yml b/packages/core/changelog/@unreleased/pr-7137.v2.yml
new file mode 100644
index 0000000000..5ddd8f0717
--- /dev/null
+++ b/packages/core/changelog/@unreleased/pr-7137.v2.yml
@@ -0,0 +1,5 @@
+type: improvement
+improvement:
+  description: Update React version check in Portal component to support React 18 and newer versions.
+  links:
+    - https://github.com/palantir/blueprint/pull/7137
diff --git a/packages/core/src/common/utils/reactUtils.ts b/packages/core/src/common/utils/reactUtils.ts
index 6ec7a1ab18..f587fb783e 100644
--- a/packages/core/src/common/utils/reactUtils.ts
+++ b/packages/core/src/common/utils/reactUtils.ts
@@ -124,6 +124,7 @@ export function isElementOfType<P = {}>(
     );
 }
 
-export function isReact18(): boolean {
-    return React.version.startsWith("18");
+export function isReact18OrHigher(): boolean {
+    const majorVersion = parseInt(React.version.split(".")[0], 10);
+    return majorVersion >= 18;
 }
diff --git a/packages/core/src/components/portal/portal.tsx b/packages/core/src/components/portal/portal.tsx
index d1a0960f67..1cacf827c1 100644
--- a/packages/core/src/components/portal/portal.tsx
+++ b/packages/core/src/components/portal/portal.tsx
@@ -20,7 +20,7 @@ import * as ReactDOM from "react-dom";
 import { Classes, DISPLAYNAME_PREFIX, type Props } from "../../common";
 import type { ValidationMap } from "../../common/context";
 import * as Errors from "../../common/errors";
-import { isReact18 } from "../../common/utils/reactUtils";
+import { isReact18OrHigher } from "../../common/utils/reactUtils";
 import { PortalContext } from "../../context/portal/portalProvider";
 
 export interface PortalProps extends Props {
@@ -157,7 +157,7 @@ export function Portal(
 
 Portal.displayName = `${DISPLAYNAME_PREFIX}.Portal`;
 // only use legacy context in React 16 or 17
-if (!isReact18()) {
+if (!isReact18OrHigher()) {
     // eslint-disable-next-line deprecation/deprecation
     Portal.contextTypes = PORTAL_LEGACY_CONTEXT_TYPES;
 }