diff --git a/extensions/ql-vscode/CHANGELOG.md b/extensions/ql-vscode/CHANGELOG.md
index 538c1713604..9c4c5e163e0 100644
--- a/extensions/ql-vscode/CHANGELOG.md
+++ b/extensions/ql-vscode/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## [UNRELEASED]
 
 - After an extension-managed CodeQL CLI update, the notification now offers to open the CLI release notes instead of the extension log. [#1095](https://github.com/github/vscode-codeql/issues/1095)
+- Remove support for CodeQL CLI versions older than 2.24.3. [#4573](https://github.com/github/vscode-codeql/pull/4573)
 
 ## 1.17.8 - 17 July 2026
 
diff --git a/extensions/ql-vscode/src/codeql-cli/cli.ts b/extensions/ql-vscode/src/codeql-cli/cli.ts
index 970b05a8ae8..5c53e4ba8cf 100644
--- a/extensions/ql-vscode/src/codeql-cli/cli.ts
+++ b/extensions/ql-vscode/src/codeql-cli/cli.ts
@@ -45,7 +45,7 @@ import type { LanguageClient } from "vscode-languageclient/node";
  * The oldest version of the CLI that we support. This is used to determine
  * whether to show a warning about the CLI being too old on startup.
  */
-export const OLDEST_SUPPORTED_CLI_VERSION = new SemVer("2.23.9");
+export const OLDEST_SUPPORTED_CLI_VERSION = new SemVer("2.24.3");
 
 /**
  * The version of the SARIF format that we are using.
diff --git a/extensions/ql-vscode/supported_cli_versions.json b/extensions/ql-vscode/supported_cli_versions.json
index 9890328e2ad..298515edc6f 100644
--- a/extensions/ql-vscode/supported_cli_versions.json
+++ b/extensions/ql-vscode/supported_cli_versions.json
@@ -3,6 +3,5 @@
   "v2.26.4",
   "v2.25.6",
   "v2.24.3",
-  "v2.23.9",
   "nightly"
 ]