diff --git a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/saml2/Saml2LoginConfiguration.java b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/saml2/Saml2LoginConfiguration.java
index c0aafc9fa9..b270cfbed7 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/saml2/Saml2LoginConfiguration.java
+++ b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/saml2/Saml2LoginConfiguration.java
@@ -17,6 +17,7 @@
 package org.springframework.boot.autoconfigure.security.saml2;
 
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
@@ -33,6 +34,7 @@ import org.springframework.security.saml2.provider.service.registration.RelyingP
 class Saml2LoginConfiguration {
 
 	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnMissingBean(WebSecurityConfigurerAdapter.class)
 	static class Saml2LoginConfigurerAdapter extends WebSecurityConfigurerAdapter {
 
 		@Override
diff --git a/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/saml2/Saml2RelyingPartyAutoConfigurationTests.java b/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/saml2/Saml2RelyingPartyAutoConfigurationTests.java
index b30c48da4a..297a36c2a9 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/saml2/Saml2RelyingPartyAutoConfigurationTests.java
+++ b/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/saml2/Saml2RelyingPartyAutoConfigurationTests.java
@@ -31,6 +31,7 @@ import org.springframework.boot.test.context.runner.WebApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.security.config.BeanIds;
+import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
 import org.springframework.security.saml2.provider.service.registration.RelyingPartyRegistration;
 import org.springframework.security.saml2.provider.service.registration.RelyingPartyRegistrationRepository;
 import org.springframework.security.saml2.provider.service.servlet.filter.Saml2WebSsoAuthenticationFilter;
@@ -104,6 +105,13 @@ public class Saml2RelyingPartyAutoConfigurationTests {
 				.run((context) -> assertThat(hasFilter(context, Saml2WebSsoAuthenticationFilter.class)).isTrue());
 	}
 
+	@Test
+	void samlLoginShouldBackOffWhenAWebSecurityConfigurerAdapterIsDefined() {
+		this.contextRunner.withUserConfiguration(WebSecurityConfigurerAdapterConfiguration.class)
+				.withPropertyValues(getPropertyValues())
+				.run((context) -> assertThat(hasFilter(context, Saml2WebSsoAuthenticationFilter.class)).isFalse());
+	}
+
 	private String[] getPropertyValues() {
 		return new String[] {
 				PREFIX + ".foo.signing.credentials[0].private-key-location=classpath:saml/private-key-location",
@@ -130,4 +138,16 @@ public class Saml2RelyingPartyAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class WebSecurityConfigurerAdapterConfiguration {
+
+		@Bean
+		WebSecurityConfigurerAdapter webSecurityConfigurerAdapter() {
+			return new WebSecurityConfigurerAdapter() {
+
+			};
+		}
+
+	}
+
 }