diff --git a/src/Api/Controllers/CollectionsController.cs b/src/Api/Controllers/CollectionsController.cs
index 9a5a12cff..8d8e737a6 100644
--- a/src/Api/Controllers/CollectionsController.cs
+++ b/src/Api/Controllers/CollectionsController.cs
@@ -4,7 +4,9 @@ using Bit.Api.Vault.AuthorizationHandlers.Collections;
 using Bit.Core;
 using Bit.Core.Context;
 using Bit.Core.Entities;
+using Bit.Core.Enums;
 using Bit.Core.Exceptions;
+using Bit.Core.Models.Data;
 using Bit.Core.OrganizationFeatures.OrganizationCollections.Interfaces;
 using Bit.Core.Repositories;
 using Bit.Core.Services;
@@ -26,6 +28,7 @@ public class CollectionsController : Controller
     private readonly ICurrentContext _currentContext;
     private readonly IBulkAddCollectionAccessCommand _bulkAddCollectionAccessCommand;
     private readonly IFeatureService _featureService;
+    private readonly IOrganizationUserRepository _organizationUserRepository;
 
     public CollectionsController(
         ICollectionRepository collectionRepository,
@@ -35,7 +38,8 @@ public class CollectionsController : Controller
         IAuthorizationService authorizationService,
         ICurrentContext currentContext,
         IBulkAddCollectionAccessCommand bulkAddCollectionAccessCommand,
-        IFeatureService featureService)
+        IFeatureService featureService,
+        IOrganizationUserRepository organizationUserRepository)
     {
         _collectionRepository = collectionRepository;
         _collectionService = collectionService;
@@ -45,6 +49,7 @@ public class CollectionsController : Controller
         _currentContext = currentContext;
         _bulkAddCollectionAccessCommand = bulkAddCollectionAccessCommand;
         _featureService = featureService;
+        _organizationUserRepository = organizationUserRepository;
     }
 
     private bool FlexibleCollectionsIsEnabled => _featureService.IsEnabled(FeatureFlagKeys.FlexibleCollections, _currentContext);
@@ -168,7 +173,29 @@ public class CollectionsController : Controller
         }
 
         var groups = model.Groups?.Select(g => g.ToSelectionReadOnly());
-        var users = model.Users?.Select(g => g.ToSelectionReadOnly());
+        var users = model.Users?.Select(g => g.ToSelectionReadOnly()).ToList() ?? new List<CollectionAccessSelection>();
+
+        // Pre-flexible collections logic assigned Managers to collections they create
+        var assignUserToCollection =
+            !FlexibleCollectionsIsEnabled &&
+            !await _currentContext.EditAnyCollection(orgId) &&
+            await _currentContext.EditAssignedCollections(orgId);
+        var isNewCollection = collection.Id == default;
+
+        if (assignUserToCollection && isNewCollection && _currentContext.UserId.HasValue)
+        {
+            var orgUser = await _organizationUserRepository.GetByOrganizationAsync(orgId, _currentContext.UserId.Value);
+            // don't add duplicate access if the user has already specified it themselves
+            var existingAccess = users.Any(u => u.Id == orgUser.Id);
+            if (orgUser is { Status: OrganizationUserStatusType.Confirmed } && !existingAccess)
+            {
+                users.Add(new CollectionAccessSelection
+                {
+                    Id = orgUser.Id,
+                    ReadOnly = false
+                });
+            }
+        }
 
         await _collectionService.SaveAsync(collection, groups, users);
         return new CollectionResponseModel(collection);
diff --git a/test/Api.Test/Controllers/LegacyCollectionsControllerTests.cs b/test/Api.Test/Controllers/LegacyCollectionsControllerTests.cs
index c07ead63f..07c27d4ab 100644
--- a/test/Api.Test/Controllers/LegacyCollectionsControllerTests.cs
+++ b/test/Api.Test/Controllers/LegacyCollectionsControllerTests.cs
@@ -3,6 +3,7 @@ using Bit.Api.Models.Request;
 using Bit.Core.AdminConsole.Entities;
 using Bit.Core.Context;
 using Bit.Core.Entities;
+using Bit.Core.Enums;
 using Bit.Core.Exceptions;
 using Bit.Core.Models.Data;
 using Bit.Core.OrganizationFeatures.OrganizationCollections.Interfaces;
@@ -12,6 +13,8 @@ using Bit.Test.Common.AutoFixture;
 using Bit.Test.Common.AutoFixture.Attributes;
 using NSubstitute;
 using Xunit;
+using Collection = Bit.Core.Entities.Collection;
+using User = Bit.Core.Entities.User;
 
 namespace Bit.Api.Test.Controllers;
 
@@ -24,8 +27,11 @@ namespace Bit.Api.Test.Controllers;
 public class LegacyCollectionsControllerTests
 {
     [Theory, BitAutoData]
-    public async Task Post_Success(Guid orgId, SutProvider<CollectionsController> sutProvider)
+    public async Task Post_Manager_AssignsToCollection_Success(Guid orgId, OrganizationUser orgUser, SutProvider<CollectionsController> sutProvider)
     {
+        orgUser.Type = OrganizationUserType.Manager;
+        orgUser.Status = OrganizationUserStatusType.Confirmed;
+
         sutProvider.GetDependency<ICurrentContext>()
             .OrganizationManager(orgId)
             .Returns(true);
@@ -34,6 +40,15 @@ public class LegacyCollectionsControllerTests
             .EditAnyCollection(orgId)
             .Returns(false);
 
+        sutProvider.GetDependency<ICurrentContext>()
+            .EditAssignedCollections(orgId)
+            .Returns(true);
+
+        sutProvider.GetDependency<ICurrentContext>().UserId = orgUser.UserId;
+
+        sutProvider.GetDependency<IOrganizationUserRepository>().GetByOrganizationAsync(orgId, orgUser.UserId.Value)
+            .Returns(orgUser);
+
         var collectionRequest = new CollectionRequestModel
         {
             Name = "encrypted_string",
@@ -42,9 +57,49 @@ public class LegacyCollectionsControllerTests
 
         _ = await sutProvider.Sut.Post(orgId, collectionRequest);
 
+        var test = sutProvider.GetDependency<ICollectionService>().ReceivedCalls();
         await sutProvider.GetDependency<ICollectionService>()
             .Received(1)
-            .SaveAsync(Arg.Any<Collection>(), Arg.Any<IEnumerable<CollectionAccessSelection>>(), null);
+            .SaveAsync(Arg.Any<Collection>(), Arg.Any<IEnumerable<CollectionAccessSelection>>(),
+                Arg.Is<IEnumerable<CollectionAccessSelection>>(users => users.Any(u => u.Id == orgUser.Id && !u.ReadOnly && !u.HidePasswords && !u.Manage)));
+    }
+
+    [Theory, BitAutoData]
+    public async Task Post_Owner_DoesNotAssignToCollection_Success(Guid orgId, OrganizationUser orgUser, SutProvider<CollectionsController> sutProvider)
+    {
+        orgUser.Type = OrganizationUserType.Owner;
+        orgUser.Status = OrganizationUserStatusType.Confirmed;
+
+        sutProvider.GetDependency<ICurrentContext>()
+            .OrganizationManager(orgId)
+            .Returns(true);
+
+        sutProvider.GetDependency<ICurrentContext>()
+            .EditAnyCollection(orgId)
+            .Returns(true);
+
+        sutProvider.GetDependency<ICurrentContext>()
+            .EditAssignedCollections(orgId)
+            .Returns(true);
+
+        sutProvider.GetDependency<ICurrentContext>().UserId = orgUser.UserId;
+
+        sutProvider.GetDependency<IOrganizationUserRepository>().GetByOrganizationAsync(orgId, orgUser.UserId.Value)
+            .Returns(orgUser);
+
+        var collectionRequest = new CollectionRequestModel
+        {
+            Name = "encrypted_string",
+            ExternalId = "my_external_id"
+        };
+
+        _ = await sutProvider.Sut.Post(orgId, collectionRequest);
+
+        var test = sutProvider.GetDependency<ICollectionService>().ReceivedCalls();
+        await sutProvider.GetDependency<ICollectionService>()
+            .Received(1)
+            .SaveAsync(Arg.Any<Collection>(), Arg.Any<IEnumerable<CollectionAccessSelection>>(),
+                Arg.Is<IEnumerable<CollectionAccessSelection>>(users => !users.Any()));
     }
 
     [Theory, BitAutoData]