diff --git a/.env.sample b/.env.sample
index dd41483..fc95ae1 100644
--- a/.env.sample
+++ b/.env.sample
@@ -29,6 +29,12 @@ COOKIE_SECRET=your-cookie-secret-here
 # Generate with: openssl rand -hex 32
 SOFARR_WEBHOOK_SECRET=your-webhook-secret-here
 
+# Public base URL of Sofarr (for webhook configuration)
+# Required for the one-click webhook setup endpoints
+# Sonarr/Radarr need this URL to know where to send webhook events
+# Example: https://sofarr.example.com or https://192.168.1.100:3001
+SOFARR_BASE_URL=https://your-sofarr-url
+
 # =============================================================================
 # TLS / HTTPS
 # =============================================================================
diff --git a/server/routes/radarr.js b/server/routes/radarr.js
index 6d74211..fcfc6e5 100644
--- a/server/routes/radarr.js
+++ b/server/routes/radarr.js
@@ -4,6 +4,7 @@ const axios = require('axios');
 const router = express.Router();
 const requireAuth = require('../middleware/requireAuth');
 const sanitizeError = require('../utils/sanitizeError');
+const { getWebhookSecret, getSofarrBaseUrl } = require('../utils/config');
 
 router.use(requireAuth);
 
@@ -56,4 +57,150 @@ router.get('/movies', async (req, res) => {
   }
 });
 
+// Notification proxy routes (Phase 3)
+// GET /api/radarr/notifications - list all notifications
+router.get('/notifications', async (req, res) => {
+  try {
+    const response = await axios.get(`${process.env.RADARR_URL}/api/v3/notification`, {
+      headers: { 'X-Api-Key': process.env.RADARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to fetch Radarr notifications', details: sanitizeError(error) });
+  }
+});
+
+// GET /api/radarr/notifications/:id - get specific notification
+router.get('/notifications/:id', async (req, res) => {
+  try {
+    const response = await axios.get(`${process.env.RADARR_URL}/api/v3/notification/${req.params.id}`, {
+      headers: { 'X-Api-Key': process.env.RADARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to fetch Radarr notification', details: sanitizeError(error) });
+  }
+});
+
+// POST /api/radarr/notifications - create notification
+router.post('/notifications', async (req, res) => {
+  try {
+    const response = await axios.post(`${process.env.RADARR_URL}/api/v3/notification`, req.body, {
+      headers: { 'X-Api-Key': process.env.RADARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to create Radarr notification', details: sanitizeError(error) });
+  }
+});
+
+// PUT /api/radarr/notifications/:id - update notification
+router.put('/notifications/:id', async (req, res) => {
+  try {
+    const response = await axios.put(`${process.env.RADARR_URL}/api/v3/notification/${req.params.id}`, req.body, {
+      headers: { 'X-Api-Key': process.env.RADARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to update Radarr notification', details: sanitizeError(error) });
+  }
+});
+
+// DELETE /api/radarr/notifications/:id - delete notification
+router.delete('/notifications/:id', async (req, res) => {
+  try {
+    const response = await axios.delete(`${process.env.RADARR_URL}/api/v3/notification/${req.params.id}`, {
+      headers: { 'X-Api-Key': process.env.RADARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to delete Radarr notification', details: sanitizeError(error) });
+  }
+});
+
+// POST /api/radarr/notifications/test - test notification
+router.post('/notifications/test', async (req, res) => {
+  try {
+    const response = await axios.post(`${process.env.RADARR_URL}/api/v3/notification/test`, req.body, {
+      headers: { 'X-Api-Key': process.env.RADARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to test Radarr notification', details: sanitizeError(error) });
+  }
+});
+
+// GET /api/radarr/notifications/schema - get notification schema
+router.get('/notifications/schema', async (req, res) => {
+  try {
+    const response = await axios.get(`${process.env.RADARR_URL}/api/v3/notification/schema`, {
+      headers: { 'X-Api-Key': process.env.RADARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to fetch Radarr notification schema', details: sanitizeError(error) });
+  }
+});
+
+// POST /api/radarr/notifications/sofarr-webhook - one-click Sofarr webhook setup
+router.post('/notifications/sofarr-webhook', async (req, res) => {
+  try {
+    const sofarrBaseUrl = getSofarrBaseUrl();
+    const webhookSecret = getWebhookSecret();
+
+    if (!sofarrBaseUrl) {
+      return res.status(400).json({ error: 'SOFARR_BASE_URL not configured' });
+    }
+    if (!webhookSecret) {
+      return res.status(400).json({ error: 'SOFARR_WEBHOOK_SECRET not configured' });
+    }
+
+    const webhookUrl = `${sofarrBaseUrl}/api/webhook/radarr`;
+
+    // Check if Sofarr webhook already exists
+    const listResponse = await axios.get(`${process.env.RADARR_URL}/api/v3/notification`, {
+      headers: { 'X-Api-Key': process.env.RADARR_API_KEY }
+    });
+    const existingNotification = listResponse.data.find(n => n.name === 'Sofarr');
+
+    const notificationPayload = {
+      name: 'Sofarr',
+      implementation: 'Webhook',
+      configContract: 'WebhookSettings',
+      fields: [
+        { name: 'url', value: webhookUrl },
+        { name: 'method', value: 'POST' },
+        { name: 'headers', value: [{ key: 'X-Sofarr-Webhook-Secret', value: webhookSecret }] }
+      ],
+      onGrab: true,
+      onDownload: true,
+      onImport: true,
+      onUpgrade: true,
+      onRename: false,
+      onHealthIssue: false,
+      onApplicationUpdate: false
+    };
+
+    if (existingNotification) {
+      // Update existing notification
+      const response = await axios.put(
+        `${process.env.RADARR_URL}/api/v3/notification/${existingNotification.id}`,
+        { ...notificationPayload, id: existingNotification.id },
+        { headers: { 'X-Api-Key': process.env.RADARR_API_KEY } }
+      );
+      res.json(response.data);
+    } else {
+      // Create new notification
+      const response = await axios.post(
+        `${process.env.RADARR_URL}/api/v3/notification`,
+        notificationPayload,
+        { headers: { 'X-Api-Key': process.env.RADARR_API_KEY } }
+      );
+      res.json(response.data);
+    }
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to configure Sofarr webhook', details: sanitizeError(error) });
+  }
+});
+
 module.exports = router;
diff --git a/server/routes/sonarr.js b/server/routes/sonarr.js
index aba4bdc..9e4d4a4 100644
--- a/server/routes/sonarr.js
+++ b/server/routes/sonarr.js
@@ -4,6 +4,7 @@ const axios = require('axios');
 const router = express.Router();
 const requireAuth = require('../middleware/requireAuth');
 const sanitizeError = require('../utils/sanitizeError');
+const { getWebhookSecret, getSofarrBaseUrl } = require('../utils/config');
 
 router.use(requireAuth);
 
@@ -56,4 +57,150 @@ router.get('/series', async (req, res) => {
   }
 });
 
+// Notification proxy routes (Phase 3)
+// GET /api/sonarr/notifications - list all notifications
+router.get('/notifications', async (req, res) => {
+  try {
+    const response = await axios.get(`${process.env.SONARR_URL}/api/v3/notification`, {
+      headers: { 'X-Api-Key': process.env.SONARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to fetch Sonarr notifications', details: sanitizeError(error) });
+  }
+});
+
+// GET /api/sonarr/notifications/:id - get specific notification
+router.get('/notifications/:id', async (req, res) => {
+  try {
+    const response = await axios.get(`${process.env.SONARR_URL}/api/v3/notification/${req.params.id}`, {
+      headers: { 'X-Api-Key': process.env.SONARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to fetch Sonarr notification', details: sanitizeError(error) });
+  }
+});
+
+// POST /api/sonarr/notifications - create notification
+router.post('/notifications', async (req, res) => {
+  try {
+    const response = await axios.post(`${process.env.SONARR_URL}/api/v3/notification`, req.body, {
+      headers: { 'X-Api-Key': process.env.SONARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to create Sonarr notification', details: sanitizeError(error) });
+  }
+});
+
+// PUT /api/sonarr/notifications/:id - update notification
+router.put('/notifications/:id', async (req, res) => {
+  try {
+    const response = await axios.put(`${process.env.SONARR_URL}/api/v3/notification/${req.params.id}`, req.body, {
+      headers: { 'X-Api-Key': process.env.SONARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to update Sonarr notification', details: sanitizeError(error) });
+  }
+});
+
+// DELETE /api/sonarr/notifications/:id - delete notification
+router.delete('/notifications/:id', async (req, res) => {
+  try {
+    const response = await axios.delete(`${process.env.SONARR_URL}/api/v3/notification/${req.params.id}`, {
+      headers: { 'X-Api-Key': process.env.SONARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to delete Sonarr notification', details: sanitizeError(error) });
+  }
+});
+
+// POST /api/sonarr/notifications/test - test notification
+router.post('/notifications/test', async (req, res) => {
+  try {
+    const response = await axios.post(`${process.env.SONARR_URL}/api/v3/notification/test`, req.body, {
+      headers: { 'X-Api-Key': process.env.SONARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to test Sonarr notification', details: sanitizeError(error) });
+  }
+});
+
+// GET /api/sonarr/notifications/schema - get notification schema
+router.get('/notifications/schema', async (req, res) => {
+  try {
+    const response = await axios.get(`${process.env.SONARR_URL}/api/v3/notification/schema`, {
+      headers: { 'X-Api-Key': process.env.SONARR_API_KEY }
+    });
+    res.json(response.data);
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to fetch Sonarr notification schema', details: sanitizeError(error) });
+  }
+});
+
+// POST /api/sonarr/notifications/sofarr-webhook - one-click Sofarr webhook setup
+router.post('/notifications/sofarr-webhook', async (req, res) => {
+  try {
+    const sofarrBaseUrl = getSofarrBaseUrl();
+    const webhookSecret = getWebhookSecret();
+
+    if (!sofarrBaseUrl) {
+      return res.status(400).json({ error: 'SOFARR_BASE_URL not configured' });
+    }
+    if (!webhookSecret) {
+      return res.status(400).json({ error: 'SOFARR_WEBHOOK_SECRET not configured' });
+    }
+
+    const webhookUrl = `${sofarrBaseUrl}/api/webhook/sonarr`;
+
+    // Check if Sofarr webhook already exists
+    const listResponse = await axios.get(`${process.env.SONARR_URL}/api/v3/notification`, {
+      headers: { 'X-Api-Key': process.env.SONARR_API_KEY }
+    });
+    const existingNotification = listResponse.data.find(n => n.name === 'Sofarr');
+
+    const notificationPayload = {
+      name: 'Sofarr',
+      implementation: 'Webhook',
+      configContract: 'WebhookSettings',
+      fields: [
+        { name: 'url', value: webhookUrl },
+        { name: 'method', value: 'POST' },
+        { name: 'headers', value: [{ key: 'X-Sofarr-Webhook-Secret', value: webhookSecret }] }
+      ],
+      onGrab: true,
+      onDownload: true,
+      onImport: true,
+      onUpgrade: true,
+      onRename: false,
+      onHealthIssue: false,
+      onApplicationUpdate: false
+    };
+
+    if (existingNotification) {
+      // Update existing notification
+      const response = await axios.put(
+        `${process.env.SONARR_URL}/api/v3/notification/${existingNotification.id}`,
+        { ...notificationPayload, id: existingNotification.id },
+        { headers: { 'X-Api-Key': process.env.SONARR_API_KEY } }
+      );
+      res.json(response.data);
+    } else {
+      // Create new notification
+      const response = await axios.post(
+        `${process.env.SONARR_URL}/api/v3/notification`,
+        notificationPayload,
+        { headers: { 'X-Api-Key': process.env.SONARR_API_KEY } }
+      );
+      res.json(response.data);
+    }
+  } catch (error) {
+    res.status(500).json({ error: 'Failed to configure Sofarr webhook', details: sanitizeError(error) });
+  }
+});
+
 module.exports = router;
diff --git a/server/utils/config.js b/server/utils/config.js
index 1d95e80..58c2c66 100644
--- a/server/utils/config.js
+++ b/server/utils/config.js
@@ -118,6 +118,10 @@ function getWebhookSecret() {
   return process.env.SOFARR_WEBHOOK_SECRET || '';
 }
 
+function getSofarrBaseUrl() {
+  return process.env.SOFARR_BASE_URL || '';
+}
+
 module.exports = {
   getSABnzbdInstances,
   getSonarrInstances,
@@ -126,6 +130,7 @@ module.exports = {
   getTransmissionInstances,
   getRtorrentInstances,
   getWebhookSecret,
+  getSofarrBaseUrl,
   parseInstances,
   validateInstanceUrl
 };