diff --git a/src/app/dashboard/financial/purchase-orders/[poId]/page.tsx b/src/app/dashboard/financial/purchase-orders/[poId]/page.tsx
index 117825e..ddc9e4b 100644
--- a/src/app/dashboard/financial/purchase-orders/[poId]/page.tsx
+++ b/src/app/dashboard/financial/purchase-orders/[poId]/page.tsx
@@ -23,13 +23,13 @@ export default async function PurchaseOrderDetailPage({
 
   let po;
   try {
-    po = await pb.collection("purchase_orders").getOne(poId, { expand: "site" });
+    po = await pb.collection("purchase_orders").getOne(poId, { expand: "site,supplier_ref" });
   } catch {
     notFound();
   }
 
   // Pull the full graph for this PO
-  const [items, dns, received] = await Promise.all([
+  const [items, dns, received, suppliers] = await Promise.all([
     pb.collection("purchase_order_items").getFullList({
       filter: `purchase_order='${poId}'`,
     }),
@@ -40,6 +40,8 @@ export default async function PurchaseOrderDetailPage({
     pb.collection("delivery_note_items").getFullList({
       fields: "id,delivery_note,purchase_order_item,qty_received,condition_notes",
     }),
+    // All suppliers, for the unknown-supplier picker on this page.
+    pb.collection("suppliers").getFullList({ sort: "name" }),
   ]);
 
   // Outstanding is computed from the delivery lines, never stored — see
@@ -116,6 +118,9 @@ export default async function PurchaseOrderDetailPage({
     projectCode: poProjectCode,
     projectName: po.expand?.site?.name ?? "",
     supplier: po.supplier,
+    supplierRefId: po.supplier_ref ?? null,
+    supplierRefName:
+      (po.expand as { supplier_ref?: { name?: string } } | undefined)?.supplier_ref?.name ?? null,
     requiredByDate: po.required_by_date,
     orderedBy: po.ordered_by,
     totalValue: po.total_value,
@@ -128,6 +133,8 @@ export default async function PurchaseOrderDetailPage({
     totalReceived,
   };
 
+  const supplierOptions = suppliers.map((s) => ({ id: s.id, name: s.name }));
+
   return (
     <>
       <Topbar
@@ -142,7 +149,7 @@ export default async function PurchaseOrderDetailPage({
           </Link>
         }
       />
-      <PoDetailView detail={detail} />
+      <PoDetailView detail={detail} suppliers={supplierOptions} />
     </>
   );
 }
\ No newline at end of file
diff --git a/src/app/dashboard/financial/purchase-orders/[poId]/po-detail-view.tsx b/src/app/dashboard/financial/purchase-orders/[poId]/po-detail-view.tsx
index 268ae4c..ab138d8 100644
--- a/src/app/dashboard/financial/purchase-orders/[poId]/po-detail-view.tsx
+++ b/src/app/dashboard/financial/purchase-orders/[poId]/po-detail-view.tsx
@@ -18,6 +18,13 @@ import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
 import { Badge } from "@/components/ui/badge";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/components/ui/select";
 import {
   Dialog,
   DialogContent,
@@ -25,7 +32,7 @@ import {
   DialogTitle,
 } from "@/components/ui/dialog";
 import { SlipPreview } from "@/components/slip-preview";
-import { cn, formatCurrency, formatNumber, isUnknownSupplier } from "@/lib/utils";
+import { cn, formatCurrency, formatNumber } from "@/lib/utils";
 import type { DeliveryNoteProcessingStatus } from "@/lib/pb-types";
 
 export interface PoDetailItem {
@@ -65,6 +72,10 @@ export interface PoDetail {
   projectCode: string;
   projectName: string;
   supplier: string;
+  /** Resolved supplier record id, if a match was made at upload or later. */
+  supplierRefId: string | null;
+  /** Display name of the linked supplier (mirrors supplierRefId's record). */
+  supplierRefName: string | null;
   requiredByDate: string;
   orderedBy: string;
   totalValue: number;
@@ -134,12 +145,22 @@ function FulfilmentBar({ pct }: { pct: number }) {
   );
 }
 
-export function PoDetailView({ detail }: { detail: PoDetail }) {
+export function PoDetailView({
+  detail,
+  suppliers,
+}: {
+  detail: PoDetail;
+  suppliers: Array<{ id: string; name: string }>;
+}) {
   const refresh = () => window.location.reload();
   const [state, setState] = React.useState<PoDetail>(detail);
   const handleSupplierSaved = React.useCallback(
-    (next: string) => {
-      setState((prev) => ({ ...prev, supplier: next }));
+    (supplierId: string, supplierName: string) => {
+      setState((prev) => ({
+        ...prev,
+        supplierRefId: supplierId,
+        supplierRefName: supplierName,
+      }));
       refresh();
     },
     [],
@@ -162,14 +183,14 @@ export function PoDetailView({ detail }: { detail: PoDetail }) {
               <h2 className="font-mono text-lg font-semibold tracking-tight">
                 {state.poNumber}
               </h2>
-              {isUnknownSupplier(state.supplier) ? (
+              {state.supplierRefId ? (
+                <span className="text-base font-medium">{state.supplierRefName}</span>
+              ) : (
                 <SupplierEditor
                   poId={state.id}
-                  currentSupplier={state.supplier}
+                  suppliers={suppliers}
                   onSaved={handleSupplierSaved}
                 />
-              ) : (
-                <span className="text-base font-medium">{state.supplier}</span>
               )}
               <Badge variant="outline" className="font-mono text-xs">
                 {state.projectCode || "—"}
@@ -500,28 +521,23 @@ function DeliveryNoteCard({
 
 function SupplierEditor({
   poId,
-  currentSupplier,
+  suppliers,
   onSaved,
 }: {
   poId: string;
-  currentSupplier: string;
-  onSaved: (next: string) => void;
+  suppliers: Array<{ id: string; name: string }>;
+  onSaved: (supplierId: string, supplierName: string) => void;
 }) {
   const [editing, setEditing] = React.useState(false);
-  const [value, setValue] = React.useState("");
+  const [selectedId, setSelectedId] = React.useState<string>("");
   const [busy, setBusy] = React.useState(false);
   const [error, setError] = React.useState<string | null>(null);
 
-  // Only render for the unknown-supplier case. Parent renders the
-  // plain <span> for known suppliers.
-  if (!isUnknownSupplier(currentSupplier)) return null;
-
-  const trimmed = value.trim();
-  const canSave = !busy && trimmed.length > 0 && trimmed.length <= 200;
+  const canSave = !busy && selectedId !== "";
 
   const cancel = () => {
     setError(null);
-    setValue("");
+    setSelectedId("");
     setEditing(false);
   };
 
@@ -533,7 +549,7 @@ function SupplierEditor({
       const res = await fetch(`/api/purchase-orders/${poId}/supplier`, {
         method: "POST",
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ supplier: trimmed }),
+        body: JSON.stringify({ supplier_id: selectedId }),
       });
       if (!res.ok) {
         const data: { error?: string } = await res
@@ -542,11 +558,10 @@ function SupplierEditor({
         setError(data.error ?? `Save failed (${res.status})`);
         return;
       }
-      const data: { supplier?: string } = await res.json();
-      const next = (data.supplier ?? trimmed).trim();
-      onSaved(next);
+      const data: { supplier_id: string; supplier_name: string } = await res.json();
+      onSaved(data.supplier_id, data.supplier_name);
       setEditing(false);
-      setValue("");
+      setSelectedId("");
     } catch (err) {
       setError(
         err instanceof Error ? err.message : "Save failed (network error)",
@@ -554,14 +569,14 @@ function SupplierEditor({
     } finally {
       setBusy(false);
     }
-  };
+  }
 
   if (!editing) {
     return (
       <button
         type="button"
         onClick={() => setEditing(true)}
-        aria-label="Edit supplier name"
+        aria-label="Assign supplier"
         className="inline-flex items-center gap-1.5 rounded-full border border-amber-500/40 bg-amber-500/15 px-2 py-0.5 text-amber-700 hover:bg-amber-500/25 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-amber-500/40 dark:text-amber-300"
       >
         <AlertTriangle className="h-3.5 w-3.5" />
@@ -573,25 +588,18 @@ function SupplierEditor({
   return (
     <div className="mt-1 flex flex-col gap-1.5">
       <div className="flex flex-wrap items-center gap-2">
-        <Input
-          autoFocus
-          value={value}
-          onChange={(e) => setValue(e.target.value)}
-          onKeyDown={(e) => {
-            if (e.key === "Escape") {
-              e.preventDefault();
-              cancel();
-            } else if (e.key === "Enter" && canSave) {
-              e.preventDefault();
-              save();
-            }
-          }}
-          placeholder="e.g. Asphaltic (Pty) Ltd"
-          maxLength={200}
-          disabled={busy}
-          className="h-8 w-64 text-sm"
-          aria-label="Supplier name"
-        />
+        <Select value={selectedId} onValueChange={setSelectedId}>
+          <SelectTrigger className="h-8 w-64 text-sm">
+            <SelectValue placeholder="Pick a supplier…" />
+          </SelectTrigger>
+          <SelectContent>
+            {suppliers.map((s) => (
+              <SelectItem key={s.id} value={s.id}>
+                {s.name}
+              </SelectItem>
+            ))}
+          </SelectContent>
+        </Select>
         <Button
           size="sm"
           onClick={save}