diff --git a/lib/DBSQLClient.ts b/lib/DBSQLClient.ts
index 8054c7c8..6164e578 100644
--- a/lib/DBSQLClient.ts
+++ b/lib/DBSQLClient.ts
@@ -1,5 +1,6 @@
 import thrift from 'thrift';
 import os from 'os';
+import tls from 'tls';
 
 import { EventEmitter } from 'events';
 import TCLIService from '../thrift/TCLIService';
@@ -196,6 +197,15 @@ export default class DBSQLClient extends EventEmitter implements IDBSQLClient, I
       https: true,
       socketTimeout: options.socketTimeout,
       proxy: options.proxy,
+      // `customCaCert` is ADDITIVE: Node's `ca` option replaces the system trust
+      // store, so we append the custom cert to the built-in roots to keep public
+      // Databricks warehouses trusted while also trusting the caller's CA.
+      ca: options.customCaCert === undefined ? undefined : [...tls.rootCertificates, options.customCaCert.toString()],
+      // Client certificate + key for mutual TLS (mTLS). Both must be supplied together.
+      cert: options.clientCert,
+      key: options.clientKey,
+      // Validate the server certificate unless the caller explicitly opts out.
+      rejectUnauthorized: options.checkServerCertificate ?? true,
       headers: {
         'User-Agent': buildUserAgentString(options.userAgentEntry),
       },
diff --git a/lib/connection/connections/HttpConnection.ts b/lib/connection/connections/HttpConnection.ts
index 8c56019c..e8a511d1 100644
--- a/lib/connection/connections/HttpConnection.ts
+++ b/lib/connection/connections/HttpConnection.ts
@@ -68,7 +68,9 @@ export default class HttpConnection implements IConnectionProvider {
     const httpsAgentOptions: https.AgentOptions = {
       ...this.getAgentDefaultOptions(),
       minVersion: 'TLSv1.2',
-      rejectUnauthorized: false,
+      // Validate the server certificate by default; only skip verification when
+      // the caller explicitly opts out via `rejectUnauthorized: false`.
+      rejectUnauthorized: this.options.rejectUnauthorized ?? true,
       ca: this.options.ca,
       cert: this.options.cert,
       key: this.options.key,
diff --git a/lib/connection/contracts/IConnectionOptions.ts b/lib/connection/contracts/IConnectionOptions.ts
index 340b6fae..cf4e9ba3 100644
--- a/lib/connection/contracts/IConnectionOptions.ts
+++ b/lib/connection/contracts/IConnectionOptions.ts
@@ -19,7 +19,11 @@ export default interface IConnectionOptions {
   socketTimeout?: number;
   proxy?: ProxyOptions;
 
-  ca?: Buffer | string;
+  ca?: Buffer | string | Array<Buffer | string>;
   cert?: Buffer | string;
   key?: Buffer | string;
+
+  // Whether the TLS server certificate is validated against the trusted CA set.
+  // When omitted the connection provider treats it as `true` (validation enabled).
+  rejectUnauthorized?: boolean;
 }
diff --git a/lib/contracts/IDBSQLClient.ts b/lib/contracts/IDBSQLClient.ts
index b1b2bb7b..3668d8d8 100644
--- a/lib/contracts/IDBSQLClient.ts
+++ b/lib/contracts/IDBSQLClient.ts
@@ -59,6 +59,46 @@ export type ConnectionOptions = {
   proxy?: ProxyOptions;
   enableMetricViewMetadata?: boolean;
 
+  /**
+   * Verify the server's TLS certificate on the primary Thrift transport.
+   * Secure-by-default: omitting this leaves full chain + hostname verification
+   * enabled (`true`), matching Node's `https` default, the JDBC/ODBC drivers,
+   * and the SEA/kernel backend.
+   *
+   * Setting it to `false` disables server certificate verification entirely
+   * (any self-signed, expired, or wrong-hostname certificate is accepted),
+   * which exposes the connection — including bearer-token auth headers — to
+   * man-in-the-middle attacks. Only use `false` for local development against a
+   * trusted endpoint, and prefer supplying `customCaCert` instead.
+   *
+   * Mirrors the `checkServerCertificate` option on the SEA backend.
+   */
+  checkServerCertificate?: boolean;
+
+  /**
+   * PEM-encoded CA certificate (string or `Buffer`) added to the trust store
+   * **on top of** the system roots — for TLS-inspecting proxies or on-prem
+   * internal CAs. Because it is additive, connections to public Databricks
+   * warehouses (trusted via the system roots) keep working.
+   *
+   * Mirrors the `customCaCert` option on the SEA backend.
+   */
+  customCaCert?: Buffer | string;
+
+  /**
+   * PEM-encoded client certificate (string or `Buffer`) presented to the server
+   * for mutual TLS (mTLS). Must be supplied together with `clientKey`. Leave
+   * both unset for the usual token/OAuth flows, which do not require a client
+   * certificate.
+   */
+  clientCert?: Buffer | string;
+
+  /**
+   * PEM-encoded private key (string or `Buffer`) for `clientCert`, used for
+   * mutual TLS (mTLS). Must be supplied together with `clientCert`.
+   */
+  clientKey?: Buffer | string;
+
   /**
    * Retry-policy knobs governing how the driver retries retryable requests.
    * They apply to **both** backends: the Thrift `HttpRetryPolicy` reads them
diff --git a/tests/unit/DBSQLClient.test.ts b/tests/unit/DBSQLClient.test.ts
index 4cf16838..7675662c 100644
--- a/tests/unit/DBSQLClient.test.ts
+++ b/tests/unit/DBSQLClient.test.ts
@@ -62,6 +62,67 @@ describe('DBSQLClient.connect', () => {
     expect(connectionOptions.path).to.equal(path);
   });
 
+  it('should validate the server certificate by default', async () => {
+    const client = new DBSQLClient();
+
+    const connectionOptions = client['getConnectionOptions'](connectOptions);
+
+    expect(connectionOptions.rejectUnauthorized).to.be.true;
+  });
+
+  it('should map checkServerCertificate to rejectUnauthorized', async () => {
+    const client = new DBSQLClient();
+
+    expect(client['getConnectionOptions']({ ...connectOptions, checkServerCertificate: false }).rejectUnauthorized).to
+      .be.false;
+    expect(client['getConnectionOptions']({ ...connectOptions, checkServerCertificate: true }).rejectUnauthorized).to.be
+      .true;
+  });
+
+  it('should not set a custom CA when customCaCert is omitted', async () => {
+    const client = new DBSQLClient();
+
+    const connectionOptions = client['getConnectionOptions'](connectOptions);
+
+    expect(connectionOptions.ca).to.be.undefined;
+  });
+
+  it('should add customCaCert on top of the system root certificates (additive)', async () => {
+    const client = new DBSQLClient();
+    const customCaCert = '-----BEGIN CERTIFICATE-----\ncustom\n-----END CERTIFICATE-----\n';
+
+    const connectionOptions = client['getConnectionOptions']({ ...connectOptions, customCaCert });
+
+    expect(connectionOptions.ca).to.be.an('array');
+    const ca = connectionOptions.ca as Array<string>;
+    // The custom cert must be present...
+    expect(ca).to.include(customCaCert);
+    // ...alongside the built-in system roots (so public warehouses still validate).
+    expect(ca.length).to.be.greaterThan(1);
+  });
+
+  it('should not set client cert/key when mTLS options are omitted', async () => {
+    const client = new DBSQLClient();
+
+    const connectionOptions = client['getConnectionOptions'](connectOptions);
+
+    expect(connectionOptions.cert).to.be.undefined;
+    expect(connectionOptions.key).to.be.undefined;
+  });
+
+  it('should map clientCert/clientKey to cert/key for mutual TLS', async () => {
+    const client = new DBSQLClient();
+
+    const connectionOptions = client['getConnectionOptions']({
+      ...connectOptions,
+      clientCert: 'client-cert',
+      clientKey: 'client-key',
+    });
+
+    expect(connectionOptions.cert).to.equal('client-cert');
+    expect(connectionOptions.key).to.equal('client-key');
+  });
+
   it('should initialize connection state', async () => {
     const client = new DBSQLClient();
 
diff --git a/tests/unit/connection/connections/HttpConnection.test.ts b/tests/unit/connection/connections/HttpConnection.test.ts
index 44d38a69..ec37e72f 100644
--- a/tests/unit/connection/connections/HttpConnection.test.ts
+++ b/tests/unit/connection/connections/HttpConnection.test.ts
@@ -26,7 +26,7 @@ describe('HttpConnection.connect', () => {
     expect(anotherConnection).to.eq(thriftConnection);
   });
 
-  it('should set SSL certificates and disable rejectUnauthorized', async () => {
+  it('should set SSL certificates and validate the server certificate by default', async () => {
     const connection = new HttpConnection(
       {
         host: 'localhost',
@@ -42,12 +42,46 @@ describe('HttpConnection.connect', () => {
 
     const thriftConnection = await connection.getThriftConnection();
 
-    expect(thriftConnection.config.agent.options.rejectUnauthorized).to.be.false;
+    expect(thriftConnection.config.agent.options.rejectUnauthorized).to.be.true;
     expect(thriftConnection.config.agent.options.ca).to.be.eq('ca');
     expect(thriftConnection.config.agent.options.cert).to.be.eq('cert');
     expect(thriftConnection.config.agent.options.key).to.be.eq('key');
   });
 
+  it('should allow disabling server certificate validation via rejectUnauthorized', async () => {
+    const connection = new HttpConnection(
+      {
+        host: 'localhost',
+        port: 10001,
+        path: '/hive',
+        https: true,
+        rejectUnauthorized: false,
+      },
+      new ClientContextStub(),
+    );
+
+    const thriftConnection = await connection.getThriftConnection();
+
+    expect(thriftConnection.config.agent.options.rejectUnauthorized).to.be.false;
+  });
+
+  it('should keep server certificate validation enabled when rejectUnauthorized is true', async () => {
+    const connection = new HttpConnection(
+      {
+        host: 'localhost',
+        port: 10001,
+        path: '/hive',
+        https: true,
+        rejectUnauthorized: true,
+      },
+      new ClientContextStub(),
+    );
+
+    const thriftConnection = await connection.getThriftConnection();
+
+    expect(thriftConnection.config.agent.options.rejectUnauthorized).to.be.true;
+  });
+
   it('should initialize http agents', async () => {
     const connection = new HttpConnection(
       {