diff --git a/src/popup/popup.css b/src/popup/popup.css
index 3d7d8a1..22a80ce 100644
--- a/src/popup/popup.css
+++ b/src/popup/popup.css
@@ -468,6 +468,18 @@ h2 {
     color: var(--danger);
 }
 
+.remove-button--undo {
+    background: rgba(37, 99, 235, 0.1);
+    color: var(--accent);
+    font-size: 12px;
+    font-weight: 800;
+}
+
+.remove-button--undo:hover {
+    background: rgba(37, 99, 235, 0.2);
+    color: var(--accent);
+}
+
 .confirm-dialog {
     width: min(318px, calc(100vw - 28px));
     padding: 0;
diff --git a/src/popup/popup.js b/src/popup/popup.js
index 75b08c1..b1edf0b 100644
--- a/src/popup/popup.js
+++ b/src/popup/popup.js
@@ -65,6 +65,7 @@ let currentUnblockChallenge = null;
 let currentBlockedRule = null;
 let currentBlockedUrl = null;
 let currentTabId = null;
+let freshRules = new Set();
 
 function createMemoryStorage() {
     let state = { blockedSites: [], temporaryUnblocks: {} };
@@ -138,13 +139,31 @@ function render(sites, temporaryUnblocks = currentTemporaryUnblocks) {
         };
 
         const remove = documentRef.createElement("button");
-        remove.className = "remove-button";
+        const isFreshRule = freshRules.has(site);
+        remove.className = isFreshRule ?
+            "remove-button remove-button--undo" :
+            "remove-button";
         remove.type = "button";
-        remove.textContent = "×";
-        remove.setAttribute("aria-label", `Remove ${site}`);
-        remove.title = "Remove blocked site";
+        remove.textContent = isFreshRule ? "Undo" : "×";
+        remove.setAttribute(
+            "aria-label",
+            isFreshRule ? `Undo adding ${site}` : `Remove ${site}`
+        );
+        remove.title = isFreshRule ?
+            "Undo adding this blocked site" :
+            "Remove blocked site";
 
         remove.onclick = () => {
+            if (isFreshRule) {
+                return removeBlockedSite(site)
+                    .then(() => {
+                        freshRules.delete(site);
+                    })
+                    .catch((error) => {
+                        setHint(getErrorMessage(error, "Could not remove blocked site."), true);
+                    });
+            }
+
             openRemoveDialog(site);
         };
 
@@ -184,13 +203,6 @@ function getCurrentUnblockableSite(sites) {
     return null;
 }
 
-function save(sites, callback) {
-    return storage.set({ blockedSites: sites }).then(() => {
-        render(sites, currentTemporaryUnblocks);
-        return callback?.();
-    });
-}
-
 function removeBlockedSite(site) {
     const nextSites = [...currentSites];
     const nextTemporaryUnblocks = { ...currentTemporaryUnblocks };
@@ -533,14 +545,21 @@ function saveRule(rule, successMessage, duplicateMessage, callback) {
             return callback?.();
         }
 
-        return save([...sites, rule], () => {
-            input.value = "";
-            setHint(successMessage);
-            return callback?.();
-        });
+        const nextSites = [...sites, rule];
+
+        return storage
+            .set({ blockedSites: nextSites })
+            .then(() => {
+                freshRules.add(rule);
+                render(nextSites, currentTemporaryUnblocks);
+                input.value = "";
+                setHint(successMessage);
+                return callback?.();
+            });
     });
 }
 
+
 async function openBlockPage(tabId, site, blockedUrl = "") {
     if (!tabId) return;
 
diff --git a/tests/unit/popup-css.test.js b/tests/unit/popup-css.test.js
index c98ba78..945dadf 100644
--- a/tests/unit/popup-css.test.js
+++ b/tests/unit/popup-css.test.js
@@ -33,6 +33,12 @@ test("popup renders a compact custom-image summary", async () => {
     );
 });
 
+test("fresh rule remove action uses undo styling", async () => {
+    const css = await readFile(new URL("../../src/popup/popup.css", import.meta.url), "utf8");
+
+    assert.match(css, /\.remove-button--undo\s*{[^}]*background:\s*rgba\(37,\s*99,\s*235,\s*0\.1\);/s);
+});
+
 function getRule(css, selector) {
     const match = css.match(new RegExp(`${selector}\\s*{([^}]*)}`));
 
diff --git a/tests/unit/popup-current-site.test.js b/tests/unit/popup-current-site.test.js
index 8e70c2d..371cd7c 100644
--- a/tests/unit/popup-current-site.test.js
+++ b/tests/unit/popup-current-site.test.js
@@ -232,6 +232,253 @@ test("popup falls back to the default preview when saved image data is invalid",
     assert.equal(elements.imageHint.classList.has("is-error"), true);
 });
 
+test("freshly added rules can be undone immediately without challenge", async (t) => {
+    const { elements, state, cleanup } = await setupPopupTest({
+        activeTab: {
+            id: 42,
+            url: "https://example.com/"
+        }
+    });
+    t.after(cleanup);
+
+    elements.siteInput.value = "example.com";
+    await elements.ruleForm.onsubmit({
+        preventDefault() {}
+    });
+
+    const removeButton = elements.list.children[0].children[2];
+    assert.equal(removeButton.textContent, "Undo");
+    assert.equal(removeButton.className.includes("remove-button--undo"), true);
+    assert.equal(removeButton["aria-label"], "Undo adding example.com");
+    assert.equal(removeButton.title, "Undo adding this blocked site");
+    assert.equal(elements.unblockDialog.open, false);
+
+    await removeButton.onclick();
+
+    assert.deepEqual(state.blockedSites, []);
+    assert.equal(elements.unblockDialog.open, false);
+    assert.equal(elements.formHint.textContent, "Blocked site removed.");
+});
+
+test("multiple fresh rules each get Undo controls and can be undone independently", async (t) => {
+    const { elements, state, cleanup } = await setupPopupTest({
+        activeTab: {
+            id: 42,
+            url: "https://example.com/"
+        }
+    });
+    t.after(cleanup);
+
+    elements.siteInput.value = "example.com";
+    await elements.ruleForm.onsubmit({
+        preventDefault() {}
+    });
+
+    elements.siteInput.value = "openai.com";
+    await elements.ruleForm.onsubmit({
+        preventDefault() {}
+    });
+
+    assert.deepEqual(state.blockedSites, ["example.com", "openai.com"]);
+
+    const firstRemoveButton = elements.list.children[0].children[2];
+    const secondRemoveButton = elements.list.children[1].children[2];
+
+    assert.equal(firstRemoveButton.textContent, "Undo");
+    assert.equal(secondRemoveButton.textContent, "Undo");
+    assert.equal(firstRemoveButton["aria-label"], "Undo adding example.com");
+    assert.equal(secondRemoveButton["aria-label"], "Undo adding openai.com");
+
+    await firstRemoveButton.onclick();
+
+    assert.deepEqual(state.blockedSites, ["openai.com"]);
+    assert.equal(elements.list.children[0].children[2].textContent, "Undo");
+});
+
+test("preloaded and duplicate rules retain the challenge-dialog removal path", async (t) => {
+    const { elements, cleanup } = await setupPopupTest({
+        activeTab: {
+            id: 42,
+            url: "https://example.com/"
+        },
+        initialState: {
+            blockedSites: ["example.com"]
+        }
+    });
+    t.after(cleanup);
+
+    elements.siteInput.value = "example.com";
+    await elements.ruleForm.onsubmit({
+        preventDefault() {}
+    });
+
+    const removeButton = elements.list.children[0].children[2];
+    assert.equal(removeButton.textContent, "×");
+    assert.equal(removeButton["aria-label"], "Remove example.com");
+    assert.equal(removeButton.title, "Remove blocked site");
+    assert.equal(elements.formHint.textContent, "This site is already in the list.");
+
+    await removeButton.onclick();
+    await Promise.resolve();
+
+    assert.equal(elements.unblockDialog.open, true);
+    assert.equal(elements.challengeDialogTitle.textContent, "Remove blocked site?");
+});
+
+test("removing a fresh rule clears temporary unblock state without challenge", async (t) => {
+    const now = 1_700_000_000_000;
+    const { elements, state, cleanup } = await setupPopupTest({
+        activeTab: {
+            id: 42,
+            url: "https://example.com/"
+        },
+        now
+    });
+    t.after(cleanup);
+
+    elements.siteInput.value = "example.com";
+    await elements.ruleForm.onsubmit({
+        preventDefault() {}
+    });
+
+    elements.currentUnblockBtn.onclick();
+    await Promise.resolve();
+    await Promise.resolve();
+    answerCurrentChallenge(elements);
+    await submitUnblockForm(elements);
+
+    assert.deepEqual(state.temporaryUnblocks, {
+        "example.com": now + 5 * 60 * 1000
+    });
+    assert.equal(elements.currentBlockStatus.textContent.startsWith("Unblocked until "), true);
+
+    const removeButton = elements.list.children[0].children[2];
+    await removeButton.onclick();
+
+    assert.deepEqual(state.temporaryUnblocks, {});
+    assert.deepEqual(state.blockedSites, []);
+    assert.equal(elements.unblockDialog.open, false);
+});
+
+test("a re-added rule is fresh again and stays undoable", async (t) => {
+    const { elements, state, cleanup } = await setupPopupTest({
+        activeTab: {
+            id: 42,
+            url: "https://example.com/"
+        }
+    });
+    t.after(cleanup);
+
+    elements.siteInput.value = "example.com";
+    await elements.ruleForm.onsubmit({
+        preventDefault() {}
+    });
+
+    const removeButton = elements.list.children[0].children[2];
+    await removeButton.onclick();
+
+    assert.deepEqual(state.blockedSites, []);
+
+    elements.siteInput.value = "example.com";
+    await elements.ruleForm.onsubmit({
+        preventDefault() {}
+    });
+
+    const readdRemoveButton = elements.list.children[0].children[2];
+    assert.equal(readdRemoveButton.textContent, "Undo");
+    await readdRemoveButton.onclick();
+    assert.deepEqual(state.blockedSites, []);
+});
+
+test("fresh rule does not stay fresh after reopening popup", async (t) => {
+    const firstSession = await setupPopupTest({
+        activeTab: {
+            id: 42,
+            url: "https://example.com/"
+        }
+    });
+    const { cleanup: cleanupFirstSession } = firstSession;
+    t.after(() => {
+        cleanupFirstSession();
+    });
+
+    firstSession.elements.siteInput.value = "example.com";
+    await firstSession.elements.ruleForm.onsubmit({
+        preventDefault() {}
+    });
+
+    assert.deepEqual(firstSession.state.blockedSites, ["example.com"]);
+
+    const { elements, state, cleanup } = await setupPopupTest({
+        activeTab: {
+            id: 42,
+            url: "https://example.com/"
+        },
+        initialState: firstSession.state
+    });
+    t.after(cleanup);
+
+    const removeButton = elements.list.children[0].children[2];
+    assert.equal(removeButton.textContent, "×");
+    assert.equal(removeButton.className.includes("remove-button--undo"), false);
+    assert.equal(removeButton["aria-label"], "Remove example.com");
+    assert.equal(removeButton.title, "Remove blocked site");
+
+    await removeButton.onclick();
+    await Promise.resolve();
+
+    assert.equal(elements.unblockDialog.open, true);
+    assert.equal(elements.challengeDialogTitle.textContent, "Remove blocked site?");
+    assert.deepEqual(state.blockedSites, ["example.com"]);
+});
+
+test("a failed fresh Undo keeps the rule and retries successfully", async (t) => {
+    const { elements, chrome, state, cleanup } = await setupPopupTest({
+        activeTab: {
+            id: 42,
+            url: "https://example.com/"
+        }
+    });
+    t.after(cleanup);
+
+    elements.siteInput.value = "example.com";
+    await elements.ruleForm.onsubmit({
+        preventDefault() {}
+    });
+
+    const removeButton = elements.list.children[0].children[2];
+    const originalSet = chrome.storage.local.set;
+    const originalLastError = chrome.runtime.lastError;
+    let shouldFail = true;
+
+    chrome.storage.local.set = (nextState, callback) => {
+        if (shouldFail) {
+            shouldFail = false;
+            chrome.runtime.lastError = { message: "Storage unavailable" };
+            callback?.();
+            return;
+        }
+
+        return originalSet(nextState, callback);
+    };
+
+    await removeButton.onclick();
+
+    assert.equal(elements.formHint.textContent, "Storage unavailable");
+    assert.equal(elements.formHint.classList.has("is-error"), true);
+    assert.equal(removeButton.textContent, "Undo");
+    assert.equal(removeButton["aria-label"], "Undo adding example.com");
+    assert.deepEqual(state.blockedSites, ["example.com"]);
+
+    chrome.storage.local.set = originalSet;
+    chrome.runtime.lastError = originalLastError;
+    await removeButton.onclick();
+
+    assert.deepEqual(state.blockedSites, []);
+    assert.equal(elements.formHint.classList.has("is-error"), false);
+    assert.equal(elements.formHint.textContent, "Blocked site removed.");
+});
+
 test("temporarily unblocking a blocked site confirms with block image preview", async (t) => {
     const now = 1_700_000_000_000;
     const { elements, chrome, state, cleanup } = await setupPopupTest({