diff --git a/src/core/config/Categories.json b/src/core/config/Categories.json
index 2602c3c09e..865ade95a4 100644
--- a/src/core/config/Categories.json
+++ b/src/core/config/Categories.json
@@ -274,7 +274,8 @@
             "Unicode Text Format",
             "Remove Diacritics",
             "Unescape Unicode Characters",
-            "Convert to NATO alphabet"
+            "Convert to NATO alphabet",
+            "Convert Leet Speak"
         ]
     },
     {
diff --git a/src/core/operations/ConvertLeetSpeak.mjs b/src/core/operations/ConvertLeetSpeak.mjs
new file mode 100644
index 0000000000..54fa62f6e7
--- /dev/null
+++ b/src/core/operations/ConvertLeetSpeak.mjs
@@ -0,0 +1,113 @@
+/**
+ * @author bartblaze []
+ * @copyright Crown Copyright 2025
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+
+/**
+ * Convert Leet Speak operation
+ */
+class ConvertLeetSpeak extends Operation {
+    /**
+     * ConvertLeetSpeak constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Convert Leet Speak";
+        this.module = "Default";
+        this.description = "Converts to and from Leet Speak";
+        this.infoURL = "https://wikipedia.org/wiki/Leet";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Direction",
+                type: "option",
+                value: ["To Leet Speak", "From Leet Speak"],
+                defaultIndex: 0
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const direction = args[0];
+        if (direction === "To Leet Speak") {
+            return input.replace(/[abcdefghijklmnopqrstuvwxyz]/gi, char => {
+                return toLeetMap[char.toLowerCase()] || char;
+            });
+        } else if (direction === "From Leet Speak") {
+            return input.replace(/[48cd3f6h1jklmn0pqr57uvwxyz]/g, char => {
+                return fromLeetMap[char] || char;
+            });
+        }
+    }
+}
+
+const toLeetMap = {
+    "a": "4",
+    "b": "b",
+    "c": "c",
+    "d": "d",
+    "e": "3",
+    "f": "f",
+    "g": "g",
+    "h": "h",
+    "i": "1",
+    "j": "j",
+    "k": "k",
+    "l": "l",
+    "m": "m",
+    "n": "n",
+    "o": "0",
+    "p": "p",
+    "q": "q",
+    "r": "r",
+    "s": "5",
+    "t": "7",
+    "u": "u",
+    "v": "v",
+    "w": "w",
+    "x": "x",
+    "y": "y",
+    "z": "z"
+};
+
+const fromLeetMap = {
+    "4": "a",
+    "b": "b",
+    "c": "c",
+    "d": "d",
+    "3": "e",
+    "f": "f",
+    "g": "g",
+    "h": "h",
+    "1": "i",
+    "j": "j",
+    "k": "k",
+    "l": "l",
+    "m": "m",
+    "n": "n",
+    "0": "o",
+    "p": "p",
+    "q": "q",
+    "r": "r",
+    "5": "s",
+    "7": "t",
+    "u": "u",
+    "v": "v",
+    "w": "w",
+    "x": "x",
+    "y": "y",
+    "z": "z"
+};
+
+export default ConvertLeetSpeak;
+
diff --git a/tests/operations/index.mjs b/tests/operations/index.mjs
index ca7509fd6f..919ad9757c 100644
--- a/tests/operations/index.mjs
+++ b/tests/operations/index.mjs
@@ -54,6 +54,7 @@ import "./tests/Comment.mjs";
 import "./tests/Compress.mjs";
 import "./tests/ConditionalJump.mjs";
 import "./tests/ConvertCoordinateFormat.mjs";
+import "./tests/ConvertLeetSpeak.mjs";
 import "./tests/ConvertToNATOAlphabet.mjs";
 import "./tests/Crypt.mjs";
 import "./tests/CSV.mjs";
diff --git a/tests/operations/tests/ConvertLeetSpeak.mjs b/tests/operations/tests/ConvertLeetSpeak.mjs
new file mode 100644
index 0000000000..198f7e57d2
--- /dev/null
+++ b/tests/operations/tests/ConvertLeetSpeak.mjs
@@ -0,0 +1,33 @@
+/**
+ * @author bartblaze []
+ * @copyright Crown Copyright 2025
+ * @license Apache-2.0
+ */
+
+import TestRegister from "../../lib/TestRegister.mjs";
+
+TestRegister.addTests([
+    {
+        name: "Convert to Leet Speak: basic text",
+        input: "leet",
+        expectedOutput: "l337",
+        recipeConfig: [
+            {
+                op: "Convert Leet Speak",
+                args: ["To Leet Speak"]
+            }
+        ]
+    },
+    {
+        name: "Convert from Leet Speak: basic leet",
+        input: "l337",
+        expectedOutput: "leet",
+        recipeConfig: [
+            {
+                op: "Convert Leet Speak",
+                args: ["From Leet Speak"]
+            }
+        ]
+    }
+]);
+