diff --git a/.last-branch b/.last-branch
index fe28a48..dad6799 100644
--- a/.last-branch
+++ b/.last-branch
@@ -1 +1 @@
-v20260115-11-autotask-companyname-unwrap
+v20260115-12-autotask-customers-refreshall-mappings
diff --git a/containers/backupchecks/src/backend/app/main/routes_customers.py b/containers/backupchecks/src/backend/app/main/routes_customers.py
index f57ca44..e54ab83 100644
--- a/containers/backupchecks/src/backend/app/main/routes_customers.py
+++ b/containers/backupchecks/src/backend/app/main/routes_customers.py
@@ -259,6 +259,73 @@ def api_customer_autotask_mapping_refresh(customer_id: int):
         return jsonify({"status": "error", "message": str(exc) or "Refresh failed."}), 400
 
 
+@main_bp.post("/api/customers/autotask-mapping/refresh-all")
+@login_required
+@roles_required("admin", "operator")
+def api_customers_autotask_mapping_refresh_all():
+    """Refresh mapping status for all customers that have an Autotask company ID."""
+
+    from ..integrations.autotask.client import AutotaskError
+
+    customers = Customer.query.filter(Customer.autotask_company_id.isnot(None)).all()
+    if not customers:
+        return jsonify({"status": "ok", "refreshed": 0, "counts": {"ok": 0, "renamed": 0, "missing": 0, "invalid": 0}})
+
+    try:
+        client = _get_autotask_client_or_raise()
+    except Exception as exc:
+        return jsonify({"status": "error", "message": str(exc) or "Autotask is not configured."}), 400
+
+    counts = {"ok": 0, "renamed": 0, "missing": 0, "invalid": 0}
+    refreshed = 0
+
+    for c in customers:
+        company_id = getattr(c, "autotask_company_id", None)
+        if not company_id:
+            continue
+        try:
+            company = client.get_company(int(company_id))
+            name = _normalize_company_name(company)
+
+            prev = (getattr(c, "autotask_company_name", None) or "").strip()
+            if prev and name and prev != name:
+                c.autotask_company_name = name
+                c.autotask_mapping_status = "renamed"
+                counts["renamed"] += 1
+            else:
+                c.autotask_company_name = name
+                c.autotask_mapping_status = "ok"
+                counts["ok"] += 1
+            c.autotask_last_sync_at = datetime.utcnow()
+            refreshed += 1
+        except AutotaskError as exc:
+            try:
+                code = getattr(exc, "status_code", None)
+            except Exception:
+                code = None
+
+            if code == 404:
+                c.autotask_mapping_status = "invalid"
+                counts["invalid"] += 1
+            else:
+                c.autotask_mapping_status = "missing"
+                counts["missing"] += 1
+            c.autotask_last_sync_at = datetime.utcnow()
+            refreshed += 1
+        except Exception:
+            c.autotask_mapping_status = "missing"
+            c.autotask_last_sync_at = datetime.utcnow()
+            counts["missing"] += 1
+            refreshed += 1
+
+    try:
+        db.session.commit()
+        return jsonify({"status": "ok", "refreshed": refreshed, "counts": counts})
+    except Exception as exc:
+        db.session.rollback()
+        return jsonify({"status": "error", "message": str(exc) or "Failed to refresh all mappings."}), 400
+
+
 @main_bp.route("/customers/create", methods=["POST"])
 @login_required
 @roles_required("admin", "operator")
diff --git a/containers/backupchecks/src/templates/main/customers.html b/containers/backupchecks/src/templates/main/customers.html
index 91ec891..024fb51 100644
--- a/containers/backupchecks/src/templates/main/customers.html
+++ b/containers/backupchecks/src/templates/main/customers.html
@@ -19,6 +19,11 @@
   </form>
 
   <a class="btn btn-outline-secondary btn-sm" href="{{ url_for('main.customers_export') }}">Export CSV</a>
+
+  {% if autotask_enabled and autotask_configured %}
+    <button type="button" class="btn btn-outline-secondary btn-sm" id="autotaskRefreshAllMappingsBtn" style="white-space: nowrap;">Refresh all Autotask mappings</button>
+    <span class="small text-muted" id="autotaskRefreshAllMappingsMsg"></span>
+  {% endif %}
 </div>
 {% endif %}
 
@@ -219,6 +224,10 @@
       var nameInput = document.getElementById("edit_customer_name");
       var activeInput = document.getElementById("edit_customer_active");
 
+      // Top-level refresh-all (only present when integration is enabled/configured)
+      var refreshAllBtn = document.getElementById("autotaskRefreshAllMappingsBtn");
+      var refreshAllMsg = document.getElementById("autotaskRefreshAllMappingsMsg");
+
       // Autotask mapping UI (only present when integration is enabled/configured)
       var atCurrent = document.getElementById("autotaskCurrentMapping");
       var atCurrentMeta = document.getElementById("autotaskCurrentMappingMeta");
@@ -233,6 +242,20 @@
       var currentCustomerId = null;
       var selectedCompanyId = null;
 
+      function setRefreshAllMsg(text, isError) {
+        if (!refreshAllMsg) {
+          return;
+        }
+        refreshAllMsg.textContent = text || "";
+        if (isError) {
+          refreshAllMsg.classList.remove("text-muted");
+          refreshAllMsg.classList.add("text-danger");
+        } else {
+          refreshAllMsg.classList.remove("text-danger");
+          refreshAllMsg.classList.add("text-muted");
+        }
+      }
+
       function setMsg(text, isError) {
         if (!atMsg) {
           return;
@@ -302,6 +325,32 @@
         return data;
       }
 
+      if (refreshAllBtn) {
+        refreshAllBtn.addEventListener("click", async function () {
+          if (!confirm("Refresh mapping status for all mapped customers?")) {
+            return;
+          }
+          refreshAllBtn.disabled = true;
+          setRefreshAllMsg("Refreshing...", false);
+          try {
+            var data = await postJson("/api/customers/autotask-mapping/refresh-all", {});
+            var counts = (data && data.counts) ? data.counts : null;
+            if (counts) {
+              setRefreshAllMsg(
+                "Done. OK: " + (counts.ok || 0) + ", Renamed: " + (counts.renamed || 0) + ", Missing: " + (counts.missing || 0) + ", Invalid: " + (counts.invalid || 0) + ".",
+                false
+              );
+            } else {
+              setRefreshAllMsg("Done.", false);
+            }
+            window.location.reload();
+          } catch (e) {
+            setRefreshAllMsg(e && e.message ? e.message : "Refresh failed.", true);
+            refreshAllBtn.disabled = false;
+          }
+        });
+      }
+
       var editButtons = document.querySelectorAll(".customer-edit-btn");
       editButtons.forEach(function (btn) {
         btn.addEventListener("click", function () {
diff --git a/docs/changelog.md b/docs/changelog.md
index ec0cd13..454b22e 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -94,6 +94,12 @@ Changes:
 - Improved company lookup handling to support different response shapes (single item and collection wrappers).
 - Ensured the cached Autotask company name is stored and displayed consistently after mapping and refresh.
 
+## v20260115-12-autotask-customers-refreshall-mappings
+
+- Added a “Refresh all Autotask mappings” button on the Customers page to validate all mapped customers in one action.
+- Implemented a new backend endpoint to refresh mapping status for all customers with an Autotask Company ID and return a status summary (ok/renamed/missing/invalid).
+- Updated the Customers UI to call the refresh-all endpoint, show a short result summary, and reload to reflect updated mapping states.
+
 ***
 
 ## v0.1.21