diff --git a/core-client/src/main/java/org/glassfish/jersey/client/innate/http/SSLParamConfigurator.java b/core-client/src/main/java/org/glassfish/jersey/client/innate/http/SSLParamConfigurator.java
index 5055c12f619..32bf44fbc79 100644
--- a/core-client/src/main/java/org/glassfish/jersey/client/innate/http/SSLParamConfigurator.java
+++ b/core-client/src/main/java/org/glassfish/jersey/client/innate/http/SSLParamConfigurator.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, 2024 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 2025 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0, which is available at
@@ -20,12 +20,14 @@
 import org.glassfish.jersey.client.ClientRequest;
 import org.glassfish.jersey.http.HttpHeaders;
 import org.glassfish.jersey.internal.PropertiesResolver;
+import org.glassfish.jersey.internal.guava.InetAddresses;
 
 import javax.net.ssl.SSLEngine;
 import javax.net.ssl.SSLParameters;
 import javax.net.ssl.SSLSocket;
 import javax.ws.rs.core.Configuration;
 import javax.ws.rs.core.UriBuilder;
+import java.net.Inet6Address;
 import java.net.InetAddress;
 import java.net.URI;
 import java.net.UnknownHostException;
@@ -233,7 +235,9 @@ public URI toIPRequestUri() {
         String host = uri.getHost();
         try {
             InetAddress ip = InetAddress.getByName(host);
-            return UriBuilder.fromUri(uri).host(ip.getHostAddress()).build();
+            // ipv6 is expected in square brackets in UriBuilder#host()
+            final String hostAddress = ip instanceof Inet6Address ? '[' + ip.getHostAddress() + ']' : ip.getHostAddress();
+            return UriBuilder.fromUri(uri).host(hostAddress).build();
         } catch (UnknownHostException e) {
             return uri;
         }
diff --git a/core-client/src/main/java/org/glassfish/jersey/client/innate/http/SniConfigurator.java b/core-client/src/main/java/org/glassfish/jersey/client/innate/http/SniConfigurator.java
index 733e4d54998..f38db94e6bf 100644
--- a/core-client/src/main/java/org/glassfish/jersey/client/innate/http/SniConfigurator.java
+++ b/core-client/src/main/java/org/glassfish/jersey/client/innate/http/SniConfigurator.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, 2024 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 2025 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0, which is available at
@@ -61,7 +61,10 @@ String getHostName() {
     static Optional<SniConfigurator> createWhenHostHeader(URI hostUri, String sniHost, boolean whenDiffer) {
         final String trimmedHeader;
         if (sniHost != null) {
-            int index = sniHost.indexOf(':'); // RFC 7230  Host = uri-host [ ":" port ] ;
+            int index = sniHost.lastIndexOf(':'); // RFC 7230  Host = uri-host [ ":" port ] ;
+            if (sniHost.indexOf(']', index) != -1) {
+                index = -1; // beware of ipv6 [:1] without port
+            }
             final String trimmedHeader0 = index != -1 ? sniHost.substring(0, index).trim() : sniHost.trim();
             trimmedHeader = trimmedHeader0.isEmpty() ? sniHost : trimmedHeader0;
         } else {
diff --git a/core-client/src/test/java/org/glassfish/jersey/client/innate/http/SSLParamConfiguratorTest.java b/core-client/src/test/java/org/glassfish/jersey/client/innate/http/SSLParamConfiguratorTest.java
index 41f8fa74c64..036eba521d8 100644
--- a/core-client/src/test/java/org/glassfish/jersey/client/innate/http/SSLParamConfiguratorTest.java
+++ b/core-client/src/test/java/org/glassfish/jersey/client/innate/http/SSLParamConfiguratorTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2024, 2025 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0, which is available at
@@ -27,8 +27,12 @@
 import org.hamcrest.Matchers;
 import org.junit.jupiter.api.Test;
 
+import javax.ws.rs.ProcessingException;
+import javax.ws.rs.client.Client;
 import javax.ws.rs.client.ClientBuilder;
 import javax.ws.rs.core.MultivaluedHashMap;
+import javax.ws.rs.core.Response;
+import java.net.ConnectException;
 import java.net.URI;
 import java.util.Collections;
 import java.util.HashMap;
@@ -155,4 +159,56 @@ public void testUriAndHeadersAndConfig() {
         MatcherAssert.assertThat(configurator.isSNIRequired(), Matchers.is(true));
         MatcherAssert.assertThat(configurator.getSNIHostName(), Matchers.is("yyy.com"));
     }
+
+    @Test
+    public void testIPv6Header() {
+        final String HOST_HEADER_IPv6 = "[172:30::333b]";
+        final URI uri = URI.create("http://[172:30::333a]:8080/api/demo/v1");
+        final JerseyClient client = (JerseyClient) ClientBuilder.newClient();
+        Map<String, List<Object>> httpHeaders = new MultivaluedHashMap<>();
+        httpHeaders.put(HttpHeaders.HOST, Collections.singletonList(HOST_HEADER_IPv6 + ":8080"));
+        SSLParamConfigurator configurator = SSLParamConfigurator.builder()
+                .uri(uri)
+                .headers(httpHeaders)
+                .configuration(client.getConfiguration())
+                .build();
+        MatcherAssert.assertThat(configurator.isSNIRequired(), Matchers.is(true));
+        MatcherAssert.assertThat(configurator.getSNIHostName(), Matchers.is(HOST_HEADER_IPv6));
+        URI expected = URI.create("http://" + HOST_HEADER_IPv6 + ":8080/api/demo/v1");
+        MatcherAssert.assertThat(configurator.getSNIUri(), Matchers.is(expected));
+        MatcherAssert.assertThat(configurator.toIPRequestUri().toString(),
+                Matchers.is(uri.toString().replace("::", ":0:0:0:0:0:")));
+    }
+
+    @Test
+    public void testIpv6Request() {
+        Client client = ClientBuilder.newClient();
+        String u = "http://[::1]:8080";
+        try {
+            client.target(u)
+                    .request()
+                    .header(HttpHeaders.HOST, "[172:30::333b]:8080")
+                    .get();
+        } catch (ProcessingException pe) {
+            if (!ConnectException.class.isInstance(pe.getCause())) {
+                throw pe;
+            }
+        }
+    }
+
+    @Test
+    public void testIpv6RequestNoPort() {
+        Client client = ClientBuilder.newClient();
+        String u = "http://[::1]";
+        try {
+            client.target(u)
+                    .request()
+                    .header(HttpHeaders.HOST, "[172:30::333b]")
+                    .get();
+        } catch (ProcessingException pe) {
+            if (!ConnectException.class.isInstance(pe.getCause())) {
+                throw pe;
+            }
+        }
+    }
 }