diff --git a/src/Api/Auth/Models/Request/OrganizationSsoRequestModel.cs b/src/Api/Auth/Models/Request/OrganizationSsoRequestModel.cs
index fcf386d7ee..349bdebb88 100644
--- a/src/Api/Auth/Models/Request/OrganizationSsoRequestModel.cs
+++ b/src/Api/Auth/Models/Request/OrganizationSsoRequestModel.cs
@@ -121,7 +121,7 @@ public class SsoConfigurationDataRequest : IValidatableObject
                     new[] { nameof(IdpEntityId) });
             }
 
-            if (!Uri.IsWellFormedUriString(IdpEntityId, UriKind.Absolute) && string.IsNullOrWhiteSpace(IdpSingleSignOnServiceUrl))
+            if (string.IsNullOrWhiteSpace(IdpSingleSignOnServiceUrl))
             {
                 yield return new ValidationResult(i18nService.GetLocalizedHtmlString("IdpSingleSignOnServiceUrlValidationError"),
                     new[] { nameof(IdpSingleSignOnServiceUrl) });
@@ -139,6 +139,7 @@ public class SsoConfigurationDataRequest : IValidatableObject
                     new[] { nameof(IdpSingleLogoutServiceUrl) });
             }
 
+            // TODO: On server, make public certificate required for SAML2 SSO: https://bitwarden.atlassian.net/browse/PM-26028
             if (!string.IsNullOrWhiteSpace(IdpX509PublicCert))
             {
                 // Validate the certificate is in a valid format
diff --git a/src/Core/Resources/SharedResources.en.resx b/src/Core/Resources/SharedResources.en.resx
index 17b4489454..28ae70ca96 100644
--- a/src/Core/Resources/SharedResources.en.resx
+++ b/src/Core/Resources/SharedResources.en.resx
@@ -389,7 +389,7 @@
     <value>If SAML Binding Type is set to artifact, identity provider resolution service URL is required.</value>
   </data>
   <data name="IdpSingleSignOnServiceUrlValidationError" xml:space="preserve">
-    <value>If Identity Provider Entity ID is not a URL, single sign on service URL is required.</value>
+    <value>Single sign on service URL is required.</value>
   </data>
   <data name="InvalidSchemeConfigurationError" xml:space="preserve">
     <value>The configured authentication scheme is not valid: "{0}"</value>
diff --git a/test/Api.Test/Auth/Models/Request/OrganizationSsoRequestModelTests.cs b/test/Api.Test/Auth/Models/Request/OrganizationSsoRequestModelTests.cs
new file mode 100644
index 0000000000..8348ba885d
--- /dev/null
+++ b/test/Api.Test/Auth/Models/Request/OrganizationSsoRequestModelTests.cs
@@ -0,0 +1,313 @@
+using System.ComponentModel.DataAnnotations;
+using Bit.Api.Auth.Models.Request.Organizations;
+using Bit.Core.Auth.Entities;
+using Bit.Core.Auth.Enums;
+using Bit.Core.Services;
+using Bit.Core.Sso;
+using Microsoft.Extensions.Localization;
+using NSubstitute;
+using Xunit;
+
+namespace Bit.Api.Test.Auth.Models.Request;
+
+public class OrganizationSsoRequestModelTests
+{
+    [Fact]
+    public void ToSsoConfig_WithOrganizationId_CreatesNewSsoConfig()
+    {
+        // Arrange
+        var organizationId = Guid.NewGuid();
+        var model = new OrganizationSsoRequestModel
+        {
+            Enabled = true,
+            Identifier = "test-identifier",
+            Data = new SsoConfigurationDataRequest
+            {
+                ConfigType = SsoType.OpenIdConnect,
+                Authority = "https://example.com",
+                ClientId = "test-client",
+                ClientSecret = "test-secret"
+            }
+        };
+
+        // Act
+        var result = model.ToSsoConfig(organizationId);
+
+        // Assert
+        Assert.NotNull(result);
+        Assert.Equal(organizationId, result.OrganizationId);
+        Assert.True(result.Enabled);
+    }
+
+    [Fact]
+    public void ToSsoConfig_WithExistingConfig_UpdatesExistingConfig()
+    {
+        // Arrange
+        var organizationId = Guid.NewGuid();
+        var existingConfig = new SsoConfig
+        {
+            Id = 1,
+            OrganizationId = organizationId,
+            Enabled = false
+        };
+
+        var model = new OrganizationSsoRequestModel
+        {
+            Enabled = true,
+            Identifier = "updated-identifier",
+            Data = new SsoConfigurationDataRequest
+            {
+                ConfigType = SsoType.Saml2,
+                IdpEntityId = "test-entity",
+                IdpSingleSignOnServiceUrl = "https://sso.example.com"
+            }
+        };
+
+        // Act
+        var result = model.ToSsoConfig(existingConfig);
+
+        // Assert
+        Assert.Same(existingConfig, result);
+        Assert.Equal(organizationId, result.OrganizationId);
+        Assert.True(result.Enabled);
+    }
+}
+
+public class SsoConfigurationDataRequestTests
+{
+    private readonly TestI18nService _i18nService;
+    private readonly ValidationContext _validationContext;
+
+    public SsoConfigurationDataRequestTests()
+    {
+        _i18nService = new TestI18nService();
+        var serviceProvider = Substitute.For<IServiceProvider>();
+        serviceProvider.GetService(typeof(II18nService)).Returns(_i18nService);
+        _validationContext = new ValidationContext(new object(), serviceProvider, null);
+    }
+
+    [Fact]
+    public void ToConfigurationData_MapsProperties()
+    {
+        // Arrange
+        var model = new SsoConfigurationDataRequest
+        {
+            ConfigType = SsoType.OpenIdConnect,
+            MemberDecryptionType = MemberDecryptionType.KeyConnector,
+            Authority = "https://authority.example.com",
+            ClientId = "test-client-id",
+            ClientSecret = "test-client-secret",
+            IdpX509PublicCert = "-----BEGIN CERTIFICATE-----\nMIIC...test\n-----END CERTIFICATE-----",
+            SpOutboundSigningAlgorithm = null // Test default
+        };
+
+        // Act
+        var result = model.ToConfigurationData();
+
+        // Assert
+        Assert.Equal(SsoType.OpenIdConnect, result.ConfigType);
+        Assert.Equal(MemberDecryptionType.KeyConnector, result.MemberDecryptionType);
+        Assert.Equal("https://authority.example.com", result.Authority);
+        Assert.Equal("test-client-id", result.ClientId);
+        Assert.Equal("test-client-secret", result.ClientSecret);
+        Assert.Equal("MIIC...test", result.IdpX509PublicCert); // PEM headers stripped
+        Assert.Equal(SamlSigningAlgorithms.Sha256, result.SpOutboundSigningAlgorithm); // Default applied
+        Assert.Null(result.IdpArtifactResolutionServiceUrl); // Always null
+    }
+
+    [Fact]
+    public void KeyConnectorEnabled_Setter_UpdatesMemberDecryptionType()
+    {
+        // Arrange
+        var model = new SsoConfigurationDataRequest();
+
+        // Act & Assert
+#pragma warning disable CS0618 // Type or member is obsolete
+        model.KeyConnectorEnabled = true;
+        Assert.Equal(MemberDecryptionType.KeyConnector, model.MemberDecryptionType);
+
+        model.KeyConnectorEnabled = false;
+        Assert.Equal(MemberDecryptionType.MasterPassword, model.MemberDecryptionType);
+#pragma warning restore CS0618 // Type or member is obsolete
+    }
+
+    // Validation Tests
+    [Fact]
+    public void Validate_OpenIdConnect_ValidData_NoErrors()
+    {
+        // Arrange
+        var model = new SsoConfigurationDataRequest
+        {
+            ConfigType = SsoType.OpenIdConnect,
+            Authority = "https://example.com",
+            ClientId = "test-client",
+            ClientSecret = "test-secret"
+        };
+
+        // Act
+        var results = model.Validate(_validationContext).ToList();
+
+        // Assert
+        Assert.Empty(results);
+    }
+
+    [Theory]
+    [InlineData("", "test-client", "test-secret", "AuthorityValidationError")]
+    [InlineData("https://example.com", "", "test-secret", "ClientIdValidationError")]
+    [InlineData("https://example.com", "test-client", "", "ClientSecretValidationError")]
+    public void Validate_OpenIdConnect_MissingRequiredFields_ReturnsErrors(string authority, string clientId, string clientSecret, string expectedError)
+    {
+        // Arrange
+        var model = new SsoConfigurationDataRequest
+        {
+            ConfigType = SsoType.OpenIdConnect,
+            Authority = authority,
+            ClientId = clientId,
+            ClientSecret = clientSecret
+        };
+
+        // Act
+        var results = model.Validate(_validationContext).ToList();
+
+        // Assert
+        Assert.Single(results);
+        Assert.Equal(expectedError, results[0].ErrorMessage);
+    }
+
+    [Fact]
+    public void Validate_Saml2_ValidData_NoErrors()
+    {
+        // Arrange
+        var model = new SsoConfigurationDataRequest
+        {
+            ConfigType = SsoType.Saml2,
+            IdpEntityId = "https://idp.example.com",
+            IdpSingleSignOnServiceUrl = "https://sso.example.com",
+            IdpSingleLogoutServiceUrl = "https://logout.example.com"
+        };
+
+        // Act
+        var results = model.Validate(_validationContext).ToList();
+
+        // Assert
+        Assert.Empty(results);
+    }
+
+    [Theory]
+    [InlineData("", "https://sso.example.com", "IdpEntityIdValidationError")]
+    [InlineData("not-a-valid-uri", "", "IdpSingleSignOnServiceUrlValidationError")]
+    public void Validate_Saml2_MissingRequiredFields_ReturnsErrors(string entityId, string signOnUrl, string expectedError)
+    {
+        // Arrange
+        var model = new SsoConfigurationDataRequest
+        {
+            ConfigType = SsoType.Saml2,
+            IdpEntityId = entityId,
+            IdpSingleSignOnServiceUrl = signOnUrl
+        };
+
+        // Act
+        var results = model.Validate(_validationContext).ToList();
+
+        // Assert
+        Assert.Contains(results, r => r.ErrorMessage == expectedError);
+    }
+
+    [Theory]
+    [InlineData("not-a-url")]
+    [InlineData("ftp://example.com")]
+    [InlineData("https://example.com<script>")]
+    [InlineData("https://example.com\"onclick")]
+    public void Validate_Saml2_InvalidUrls_ReturnsErrors(string invalidUrl)
+    {
+        // Arrange
+        var model = new SsoConfigurationDataRequest
+        {
+            ConfigType = SsoType.Saml2,
+            IdpEntityId = "https://idp.example.com",
+            IdpSingleSignOnServiceUrl = invalidUrl,
+            IdpSingleLogoutServiceUrl = invalidUrl
+        };
+
+        // Act
+        var results = model.Validate(_validationContext).ToList();
+
+        // Assert
+        Assert.Contains(results, r => r.ErrorMessage == "IdpSingleSignOnServiceUrlInvalid");
+        Assert.Contains(results, r => r.ErrorMessage == "IdpSingleLogoutServiceUrlInvalid");
+    }
+
+    [Fact]
+    public void Validate_Saml2_MissingSignOnUrl_AlwaysReturnsError()
+    {
+        // Arrange - SignOnUrl is always required for SAML2, regardless of EntityId format
+        var model = new SsoConfigurationDataRequest
+        {
+            ConfigType = SsoType.Saml2,
+            IdpEntityId = "https://idp.example.com", // Valid URI
+            IdpSingleSignOnServiceUrl = "" // Missing - always causes error
+        };
+
+        // Act
+        var results = model.Validate(_validationContext).ToList();
+
+        // Assert - Should always fail validation when SignOnUrl is missing
+        Assert.Contains(results, r => r.ErrorMessage == "IdpSingleSignOnServiceUrlValidationError");
+    }
+
+    [Fact]
+    public void Validate_Saml2_InvalidCertificate_ReturnsError()
+    {
+        // Arrange
+        var model = new SsoConfigurationDataRequest
+        {
+            ConfigType = SsoType.Saml2,
+            IdpEntityId = "https://idp.example.com",
+            IdpSingleSignOnServiceUrl = "https://sso.example.com",
+            IdpX509PublicCert = "invalid-certificate-data"
+        };
+
+        // Act
+        var results = model.Validate(_validationContext).ToList();
+
+        // Assert
+        Assert.Contains(results, r => r.ErrorMessage.Contains("IdpX509PublicCert") && r.ErrorMessage.Contains("ValidationError"));
+    }
+
+    // TODO: On server, make public certificate required for SAML2 SSO: https://bitwarden.atlassian.net/browse/PM-26028
+    [Fact]
+    public void Validate_Saml2_EmptyCertificate_PassesValidation()
+    {
+        // Arrange
+        var model = new SsoConfigurationDataRequest
+        {
+            ConfigType = SsoType.Saml2,
+            IdpEntityId = "https://idp.example.com",
+            IdpSingleSignOnServiceUrl = "https://sso.example.com",
+            IdpX509PublicCert = ""
+        };
+
+        // Act
+        var results = model.Validate(_validationContext).ToList();
+
+        // Assert
+        Assert.DoesNotContain(results, r => r.MemberNames.Contains("IdpX509PublicCert"));
+    }
+
+    private class TestI18nService : I18nService
+    {
+        public TestI18nService() : base(CreateMockLocalizerFactory()) { }
+
+        private static IStringLocalizerFactory CreateMockLocalizerFactory()
+        {
+            var factory = Substitute.For<IStringLocalizerFactory>();
+            var localizer = Substitute.For<IStringLocalizer>();
+
+            localizer[Arg.Any<string>()].Returns(callInfo => new LocalizedString(callInfo.Arg<string>(), callInfo.Arg<string>()));
+            localizer[Arg.Any<string>(), Arg.Any<object[]>()].Returns(callInfo => new LocalizedString(callInfo.Arg<string>(), callInfo.Arg<string>()));
+
+            factory.Create(Arg.Any<string>(), Arg.Any<string>()).Returns(localizer);
+            return factory;
+        }
+    }
+}