diff --git a/java/ql/lib/change-notes/2026-02-12-deprecate-unreachableblocks.md b/java/ql/lib/change-notes/2026-02-12-deprecate-unreachableblocks.md
new file mode 100644
index 000000000000..24748cbb09ec
--- /dev/null
+++ b/java/ql/lib/change-notes/2026-02-12-deprecate-unreachableblocks.md
@@ -0,0 +1,4 @@
+---
+category: deprecated
+---
+* The `UnreachableBlocks.qll` library has been deprecated.
diff --git a/java/ql/lib/semmle/code/java/controlflow/UnreachableBlocks.qll b/java/ql/lib/semmle/code/java/controlflow/UnreachableBlocks.qll
index dfc9fc2833bd..6ac7668266ea 100644
--- a/java/ql/lib/semmle/code/java/controlflow/UnreachableBlocks.qll
+++ b/java/ql/lib/semmle/code/java/controlflow/UnreachableBlocks.qll
@@ -1,8 +1,10 @@
 /**
+ * DEPRECATED: This module is no longer maintained, and will be removed in a future release.
+ *
  * Provides classes and predicates for identifying unreachable blocks under a "closed-world" assumption.
  */
 overlay[local?]
-module;
+deprecated module;
 
 import java
 import semmle.code.java.controlflow.Guards
diff --git a/java/ql/lib/semmle/code/java/controlflow/unreachableblocks/ExcludeDebuggingProfilingLogging.qll b/java/ql/lib/semmle/code/java/controlflow/unreachableblocks/ExcludeDebuggingProfilingLogging.qll
index bda7f9bee740..8958ceedb324 100644
--- a/java/ql/lib/semmle/code/java/controlflow/unreachableblocks/ExcludeDebuggingProfilingLogging.qll
+++ b/java/ql/lib/semmle/code/java/controlflow/unreachableblocks/ExcludeDebuggingProfilingLogging.qll
@@ -1,5 +1,8 @@
+/**
+ * DEPRECATED: This module is no longer maintained, and will be removed in a future release.
+ */
 overlay[local?]
-module;
+deprecated module;
 
 import java
 import semmle.code.java.controlflow.UnreachableBlocks
diff --git a/java/ql/test/library-tests/unreachableblocks/UnreachableBlocks.expected b/java/ql/test/library-tests/unreachableblocks/UnreachableBlocks.expected
deleted file mode 100644
index acf240ae3136..000000000000
--- a/java/ql/test/library-tests/unreachableblocks/UnreachableBlocks.expected
+++ /dev/null
@@ -1,12 +0,0 @@
-| unreachableblocks/Unreachable.java:3:14:3:24 | Exceptional Exit |
-| unreachableblocks/Unreachable.java:3:14:3:24 | Exceptional Exit |
-| unreachableblocks/Unreachable.java:5:14:5:19 | Exceptional Exit |
-| unreachableblocks/Unreachable.java:6:14:8:3 | { ... } |
-| unreachableblocks/Unreachable.java:9:21:11:3 | { ... } |
-| unreachableblocks/Unreachable.java:12:22:14:3 | { ... } |
-| unreachableblocks/Unreachable.java:17:3:17:9 | case ... |
-| unreachableblocks/Unreachable.java:19:3:19:9 | case ... |
-| unreachableblocks/Unreachable.java:24:3:24:9 | case ... |
-| unreachableblocks/Unreachable.java:26:3:26:10 | case ... |
-| unreachableblocks/Unreachable.java:27:3:27:10 | default |
-| unreachableblocks/Unreachable.java:32:18:32:28 | Exceptional Exit |
diff --git a/java/ql/test/library-tests/unreachableblocks/UnreachableBlocks.ql b/java/ql/test/library-tests/unreachableblocks/UnreachableBlocks.ql
deleted file mode 100644
index b7229c059f36..000000000000
--- a/java/ql/test/library-tests/unreachableblocks/UnreachableBlocks.ql
+++ /dev/null
@@ -1,5 +0,0 @@
-import default
-import semmle.code.java.controlflow.UnreachableBlocks
-
-from UnreachableBasicBlock unreachableBasicBlock
-select unreachableBasicBlock
diff --git a/java/ql/test/library-tests/unreachableblocks/unreachableblocks/Unreachable.java b/java/ql/test/library-tests/unreachableblocks/unreachableblocks/Unreachable.java
deleted file mode 100644
index a8dc419975bf..000000000000
--- a/java/ql/test/library-tests/unreachableblocks/unreachableblocks/Unreachable.java
+++ /dev/null
@@ -1,35 +0,0 @@
-package unreachableblocks;
-
-public class Unreachable {
-	private boolean privateFalse = false;
-	public void method() {
-		if (false) {
-			// unreachable
-		}
-		if (privateFalse) {
-			// unreachable
-		}
-		if (methodFalse()) {
-			// unreachable
-		}
-
-		switch (7) {
-		case 5: // unreachable
-			break;
-		case 6: // unreachable
-			System.out.println("dead"); // unreachable
-		case 7:
-		case 8: // reachable from 7
-			break; // reachable
-		case 9: //unreachable
-			break;
-		case 10: // unreachable
-		default:
-			break; //unreachable
-		}
-	}
-
-	private boolean methodFalse() {
-		return privateFalse;
-	}
-}
\ No newline at end of file