diff --git a/src/app/(dashboard)/settings/workspace/components/workspace-form.tsx b/src/app/(dashboard)/settings/workspace/components/workspace-form.tsx
new file mode 100644
index 0000000..7e6a758
--- /dev/null
+++ b/src/app/(dashboard)/settings/workspace/components/workspace-form.tsx
@@ -0,0 +1,192 @@
+"use client";
+
+import { useActionState, useEffect } from "react";
+import { Building2, Loader2, Receipt, Save } from "lucide-react";
+import { toast } from "sonner";
+
+import { Button } from "@/components/ui/button";
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+import { Textarea } from "@/components/ui/textarea";
+import { updateWorkspaceSettingsAction } from "@/lib/appwrite/workspace-actions";
+import { initialWorkspaceSettingsState } from "@/lib/appwrite/workspace-types";
+
+type Defaults = {
+  companyName: string;
+  companyTaxId: string;
+  companyAddress: string;
+  companyEmail: string;
+  companyPhone: string;
+  defaultVatRate: number;
+  invoicePrefix: string;
+  invoiceCounter: number;
+};
+
+export function WorkspaceSettingsForm({
+  canEdit,
+  defaults,
+}: {
+  canEdit: boolean;
+  defaults: Defaults;
+}) {
+  const [state, formAction, isPending] = useActionState(
+    updateWorkspaceSettingsAction,
+    initialWorkspaceSettingsState,
+  );
+
+  useEffect(() => {
+    if (state.ok) toast.success("Bilgiler güncellendi.");
+    else if (state.error) toast.error(state.error);
+  }, [state]);
+
+  return (
+    <form action={formAction} className="space-y-6">
+      <fieldset disabled={!canEdit || isPending} className="space-y-6 disabled:opacity-90">
+        <Card>
+          <CardHeader>
+            <CardTitle className="flex items-center gap-2">
+              <Building2 className="size-4" />
+              Şirket
+            </CardTitle>
+            <CardDescription>Resmi şirket bilgileriniz.</CardDescription>
+          </CardHeader>
+          <CardContent className="grid gap-5 md:grid-cols-2">
+            <div className="md:col-span-2 grid gap-2">
+              <Label htmlFor="companyName">Şirket adı *</Label>
+              <Input
+                id="companyName"
+                name="companyName"
+                defaultValue={defaults.companyName}
+                required
+                placeholder="Örn. Acme Yazılım Ltd. Şti."
+              />
+              {state.fieldErrors?.companyName && (
+                <p className="text-destructive text-xs">{state.fieldErrors.companyName}</p>
+              )}
+            </div>
+
+            <div className="grid gap-2">
+              <Label htmlFor="companyTaxId">Vergi numarası</Label>
+              <Input
+                id="companyTaxId"
+                name="companyTaxId"
+                defaultValue={defaults.companyTaxId}
+                inputMode="numeric"
+                placeholder="1234567890"
+              />
+            </div>
+
+            <div className="grid gap-2">
+              <Label htmlFor="companyPhone">Telefon</Label>
+              <Input
+                id="companyPhone"
+                name="companyPhone"
+                type="tel"
+                defaultValue={defaults.companyPhone}
+                placeholder="+90 555 123 45 67"
+              />
+            </div>
+
+            <div className="grid gap-2">
+              <Label htmlFor="companyEmail">Email</Label>
+              <Input
+                id="companyEmail"
+                name="companyEmail"
+                type="email"
+                defaultValue={defaults.companyEmail}
+                placeholder="info@firma.com"
+              />
+              {state.fieldErrors?.companyEmail && (
+                <p className="text-destructive text-xs">{state.fieldErrors.companyEmail}</p>
+              )}
+            </div>
+
+            <div className="grid gap-2">
+              <Label htmlFor="companyAddress">Adres</Label>
+              <Textarea
+                id="companyAddress"
+                name="companyAddress"
+                rows={2}
+                defaultValue={defaults.companyAddress}
+                placeholder="İl, ilçe, açık adres"
+              />
+            </div>
+          </CardContent>
+        </Card>
+
+        <Card>
+          <CardHeader>
+            <CardTitle className="flex items-center gap-2">
+              <Receipt className="size-4" />
+              Faturalama
+            </CardTitle>
+            <CardDescription>
+              Yeni fatura oluştururken kullanılan varsayılanlar.
+            </CardDescription>
+          </CardHeader>
+          <CardContent className="grid gap-5 md:grid-cols-3">
+            <div className="grid gap-2">
+              <Label htmlFor="invoicePrefix">Fatura ön eki</Label>
+              <Input
+                id="invoicePrefix"
+                name="invoicePrefix"
+                defaultValue={defaults.invoicePrefix}
+                maxLength={10}
+                placeholder="INV"
+                style={{ textTransform: "uppercase" }}
+              />
+              <p className="text-muted-foreground text-xs">
+                Örn. <code>INV-2026-0001</code>
+              </p>
+            </div>
+
+            <div className="grid gap-2">
+              <Label htmlFor="defaultVatRate">Varsayılan KDV %</Label>
+              <Input
+                id="defaultVatRate"
+                name="defaultVatRate"
+                type="number"
+                step="0.1"
+                min="0"
+                max="100"
+                defaultValue={defaults.defaultVatRate}
+              />
+              {state.fieldErrors?.defaultVatRate && (
+                <p className="text-destructive text-xs">{state.fieldErrors.defaultVatRate}</p>
+              )}
+            </div>
+
+            <div className="grid gap-2">
+              <Label>Sayaç</Label>
+              <div className="bg-muted/50 flex h-9 items-center rounded-md border px-3 text-sm tabular-nums">
+                {defaults.invoiceCounter}
+              </div>
+              <p className="text-muted-foreground text-xs">
+                Bir sonraki fatura numarası: bu sayı + 1
+              </p>
+            </div>
+          </CardContent>
+        </Card>
+
+        {canEdit && (
+          <div className="flex justify-end">
+            <Button type="submit" disabled={isPending}>
+              {isPending ? (
+                <>
+                  <Loader2 className="size-4 animate-spin" />
+                  Kaydediliyor...
+                </>
+              ) : (
+                <>
+                  <Save className="size-4" />
+                  Kaydet
+                </>
+              )}
+            </Button>
+          </div>
+        )}
+      </fieldset>
+    </form>
+  );
+}
diff --git a/src/app/(dashboard)/settings/workspace/page.tsx b/src/app/(dashboard)/settings/workspace/page.tsx
new file mode 100644
index 0000000..4567287
--- /dev/null
+++ b/src/app/(dashboard)/settings/workspace/page.tsx
@@ -0,0 +1,50 @@
+import type { Metadata } from "next";
+import { redirect } from "next/navigation";
+
+import { requireTenant } from "@/lib/appwrite/tenant-guard";
+import { WorkspaceSettingsForm } from "./components/workspace-form";
+
+export const metadata: Metadata = {
+  title: "İşletmem — Şirket bilgileri",
+};
+
+export default async function WorkspaceSettingsPage() {
+  let ctx;
+  try {
+    ctx = await requireTenant();
+  } catch {
+    redirect("/onboarding");
+  }
+
+  const canEdit = ctx.role === "owner" || ctx.role === "admin";
+
+  return (
+    <div className="flex-1 space-y-6 px-6 pt-0">
+      <div className="flex flex-col gap-1">
+        <p className="text-muted-foreground text-sm">{ctx.settings?.companyName ?? "Çalışma alanı"}</p>
+        <h1 className="text-2xl font-bold tracking-tight">Şirket bilgileri</h1>
+        <p className="text-muted-foreground text-sm">
+          Faturalarda ve panel başlığında görünecek şirket bilgileri.
+          {!canEdit && " Düzenlemek için yönetici yetkisine ihtiyacınız var."}
+        </p>
+      </div>
+
+      <WorkspaceSettingsForm
+        canEdit={canEdit}
+        defaults={{
+          companyName: ctx.settings?.companyName ?? "",
+          companyTaxId: ctx.settings?.companyTaxId ?? "",
+          companyAddress: ctx.settings?.companyAddress ?? "",
+          companyEmail: ctx.settings?.companyEmail ?? "",
+          companyPhone: ctx.settings?.companyPhone ?? "",
+          defaultVatRate:
+            typeof ctx.settings?.defaultVatRate === "number"
+              ? ctx.settings.defaultVatRate
+              : 20,
+          invoicePrefix: ctx.settings?.invoicePrefix ?? "INV",
+          invoiceCounter: ctx.settings?.invoiceCounter ?? 0,
+        }}
+      />
+    </div>
+  );
+}
diff --git a/src/lib/appwrite/workspace-actions.ts b/src/lib/appwrite/workspace-actions.ts
new file mode 100644
index 0000000..05cfab9
--- /dev/null
+++ b/src/lib/appwrite/workspace-actions.ts
@@ -0,0 +1,106 @@
+"use server";
+
+import { revalidatePath } from "next/cache";
+import { AppwriteException, ID, Permission, Query, Role } from "node-appwrite";
+import { z } from "zod";
+
+import { logAudit } from "./audit";
+import { DATABASE_ID, TABLES, type TenantSettings } from "./schema";
+import { createAdminClient } from "./server";
+import { requireRole, requireTenant } from "./tenant-guard";
+import type { WorkspaceSettingsState } from "./workspace-types";
+import { workspaceSettingsSchema } from "@/lib/validation/workspace";
+
+function appwriteError(e: unknown): string {
+  if (e instanceof AppwriteException) return e.message || "Beklenmeyen hata.";
+  return "Bağlantı hatası. Tekrar deneyin.";
+}
+
+function flattenErrors(err: z.ZodError): Record<string, string> {
+  const out: Record<string, string> = {};
+  for (const issue of err.issues) {
+    const key = issue.path.join(".");
+    if (key && !out[key]) out[key] = issue.message;
+  }
+  return out;
+}
+
+function pickFormFields(formData: FormData) {
+  return {
+    companyName: String(formData.get("companyName") ?? "").trim(),
+    companyTaxId: String(formData.get("companyTaxId") ?? "").trim(),
+    companyAddress: String(formData.get("companyAddress") ?? "").trim(),
+    companyEmail: String(formData.get("companyEmail") ?? "").trim(),
+    companyPhone: String(formData.get("companyPhone") ?? "").trim(),
+    defaultVatRate: String(formData.get("defaultVatRate") ?? "20"),
+    invoicePrefix: String(formData.get("invoicePrefix") ?? "").trim(),
+  };
+}
+
+export async function updateWorkspaceSettingsAction(
+  _prev: WorkspaceSettingsState,
+  formData: FormData,
+): Promise<WorkspaceSettingsState> {
+  let ctx;
+  try {
+    ctx = await requireTenant();
+    requireRole(ctx, ["owner", "admin"]);
+  } catch {
+    return { ok: false, error: "Düzenleme yetkiniz yok." };
+  }
+
+  const parsed = workspaceSettingsSchema.safeParse(pickFormFields(formData));
+  if (!parsed.success) {
+    return { ok: false, error: "Form geçersiz.", fieldErrors: flattenErrors(parsed.error) };
+  }
+
+  try {
+    const { tablesDB } = createAdminClient();
+
+    const existing = await tablesDB.listRows({
+      databaseId: DATABASE_ID,
+      tableId: TABLES.tenantSettings,
+      queries: [Query.equal("tenantId", ctx.tenantId), Query.limit(1)],
+    });
+    const row = existing.rows[0] as unknown as TenantSettings | undefined;
+
+    if (row) {
+      await tablesDB.updateRow(DATABASE_ID, TABLES.tenantSettings, row.$id, parsed.data);
+      await logAudit({
+        tenantId: ctx.tenantId,
+        userId: ctx.user.id,
+        action: "update",
+        entityType: "tenant_settings",
+        entityId: row.$id,
+        changes: parsed.data,
+      });
+    } else {
+      const created = await tablesDB.createRow(
+        DATABASE_ID,
+        TABLES.tenantSettings,
+        ID.unique(),
+        { tenantId: ctx.tenantId, ...parsed.data },
+        [
+          Permission.read(Role.team(ctx.tenantId)),
+          Permission.update(Role.team(ctx.tenantId, "owner")),
+          Permission.update(Role.team(ctx.tenantId, "admin")),
+          Permission.delete(Role.team(ctx.tenantId, "owner")),
+        ],
+      );
+      await logAudit({
+        tenantId: ctx.tenantId,
+        userId: ctx.user.id,
+        action: "create",
+        entityType: "tenant_settings",
+        entityId: created.$id,
+        changes: parsed.data,
+      });
+    }
+  } catch (e) {
+    return { ok: false, error: appwriteError(e) };
+  }
+
+  // Tenant name shows up everywhere — revalidate broadly
+  revalidatePath("/", "layout");
+  return { ok: true };
+}
diff --git a/src/lib/appwrite/workspace-types.ts b/src/lib/appwrite/workspace-types.ts
new file mode 100644
index 0000000..f2bf218
--- /dev/null
+++ b/src/lib/appwrite/workspace-types.ts
@@ -0,0 +1,7 @@
+export type WorkspaceSettingsState = {
+  ok: boolean;
+  error?: string;
+  fieldErrors?: Record<string, string>;
+};
+
+export const initialWorkspaceSettingsState: WorkspaceSettingsState = { ok: false };
diff --git a/src/lib/validation/workspace.ts b/src/lib/validation/workspace.ts
new file mode 100644
index 0000000..52611bb
--- /dev/null
+++ b/src/lib/validation/workspace.ts
@@ -0,0 +1,44 @@
+import { z } from "zod";
+
+export const workspaceSettingsSchema = z.object({
+  companyName: z.string().trim().min(1, "Şirket adı zorunlu.").max(255),
+  companyTaxId: z
+    .string()
+    .trim()
+    .max(50)
+    .optional()
+    .transform((v) => (v ? v : undefined)),
+  companyAddress: z
+    .string()
+    .trim()
+    .max(500)
+    .optional()
+    .transform((v) => (v ? v : undefined)),
+  companyEmail: z
+    .union([z.string().email("Geçerli bir email girin."), z.literal("")])
+    .optional()
+    .transform((v) => (v ? v : undefined)),
+  companyPhone: z
+    .string()
+    .trim()
+    .max(30)
+    .optional()
+    .transform((v) => (v ? v : undefined)),
+  defaultVatRate: z
+    .union([z.number(), z.string()])
+    .optional()
+    .transform((v) => {
+      if (v === undefined || v === "") return 20;
+      const n = typeof v === "string" ? Number(v.replace(",", ".")) : v;
+      return Number.isFinite(n) ? n : 20;
+    })
+    .pipe(z.number().min(0, "Negatif olamaz.").max(100, "100'den büyük olamaz.")),
+  invoicePrefix: z
+    .string()
+    .trim()
+    .max(10)
+    .optional()
+    .transform((v) => (v ? v.toUpperCase() : "INV")),
+});
+
+export type WorkspaceSettingsInput = z.infer<typeof workspaceSettingsSchema>;