diff --git a/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/QuarkusRestClientBuilder.java b/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/QuarkusRestClientBuilder.java
index a7c66165bea7f..c67adff8fa9e9 100644
--- a/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/QuarkusRestClientBuilder.java
+++ b/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/QuarkusRestClientBuilder.java
@@ -178,6 +178,14 @@ static QuarkusRestClientBuilder newBuilder() {
      */
     QuarkusRestClientBuilder followRedirects(boolean follow);
 
+    /**
+     * Mode in which the form data are encoded. Possible values are `HTML5`, `RFC1738` and `RFC3986`.
+     * The modes are described in the
+     * <a href="https://netty.io/4.1/api/io/netty/handler/codec/http/multipart/HttpPostRequestEncoder.EncoderMode.html">Netty
+     * documentation</a>
+     */
+    QuarkusRestClientBuilder multipartPostEncoderMode(String mode);
+
     /**
      * Specifies the HTTP proxy hostname/IP address and port to use for requests from client instances.
      *
diff --git a/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/runtime/QuarkusRestClientBuilderImpl.java b/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/runtime/QuarkusRestClientBuilderImpl.java
index 3ba9ad115f961..5a663f92641c4 100644
--- a/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/runtime/QuarkusRestClientBuilderImpl.java
+++ b/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/runtime/QuarkusRestClientBuilderImpl.java
@@ -120,6 +120,12 @@ public QuarkusRestClientBuilder nonProxyHosts(String nonProxyHosts) {
         return this;
     }
 
+    @Override
+    public QuarkusRestClientBuilder multipartPostEncoderMode(String mode) {
+        proxy.multipartPostEncoderMode(mode);
+        return this;
+    }
+
     @Override
     public QuarkusRestClientBuilder queryParamStyle(QueryParamStyle style) {
         proxy.queryParamStyle(style);
diff --git a/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/runtime/RestClientBuilderImpl.java b/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/runtime/RestClientBuilderImpl.java
index 3920c8db594c1..daa221114c341 100644
--- a/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/runtime/RestClientBuilderImpl.java
+++ b/extensions/resteasy-reactive/rest-client/runtime/src/main/java/io/quarkus/rest/client/reactive/runtime/RestClientBuilderImpl.java
@@ -10,6 +10,7 @@
 import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.TimeUnit;
@@ -34,6 +35,7 @@
 import org.jboss.resteasy.reactive.client.impl.ClientBuilderImpl;
 import org.jboss.resteasy.reactive.client.impl.ClientImpl;
 import org.jboss.resteasy.reactive.client.impl.WebTargetImpl;
+import org.jboss.resteasy.reactive.client.impl.multipart.PausableHttpPostRequestEncoder;
 import org.jboss.resteasy.reactive.common.jaxrs.ConfigurationImpl;
 import org.jboss.resteasy.reactive.common.jaxrs.MultiQueryParamMode;
 
@@ -63,6 +65,7 @@ public class RestClientBuilderImpl implements RestClientBuilder {
     private boolean followRedirects;
     private QueryParamStyle queryParamStyle;
 
+    private String multipartPostEncoderMode;
     private String proxyHost;
     private Integer proxyPort;
     private String proxyUser;
@@ -167,6 +170,11 @@ public RestClientBuilderImpl nonProxyHosts(String nonProxyHosts) {
         return this;
     }
 
+    public RestClientBuilderImpl multipartPostEncoderMode(String mode) {
+        this.multipartPostEncoderMode = mode;
+        return this;
+    }
+
     public RestClientBuilderImpl clientLogger(ClientLogger clientLogger) {
         this.clientLogger = clientLogger;
         return this;
@@ -435,6 +443,21 @@ public <T> T build(Class<T> aClass) throws IllegalStateException, RestClientDefi
             configureProxy(globalProxy.host, globalProxy.port, restClientsConfig.proxyUser.orElse(null),
                     restClientsConfig.proxyPassword.orElse(null), restClientsConfig.nonProxyHosts.orElse(null));
         }
+
+        if (!clientBuilder.getConfiguration().hasProperty(QuarkusRestClientProperties.MULTIPART_ENCODER_MODE)) {
+            PausableHttpPostRequestEncoder.EncoderMode multipartPostEncoderMode = null;
+            if (this.multipartPostEncoderMode != null) {
+                multipartPostEncoderMode = PausableHttpPostRequestEncoder.EncoderMode
+                        .valueOf(this.multipartPostEncoderMode.toUpperCase(Locale.ROOT));
+            } else if (restClientsConfig.multipartPostEncoderMode.isPresent()) {
+                multipartPostEncoderMode = PausableHttpPostRequestEncoder.EncoderMode
+                        .valueOf(restClientsConfig.multipartPostEncoderMode.get().toUpperCase(Locale.ROOT));
+            }
+            if (multipartPostEncoderMode != null) {
+                clientBuilder.property(QuarkusRestClientProperties.MULTIPART_ENCODER_MODE, multipartPostEncoderMode);
+            }
+        }
+
         ClientImpl client = clientBuilder.build();
         WebTargetImpl target = (WebTargetImpl) client.target(uri);
         target.setParamConverterProviders(paramConverterProviders);