Does ArcGIS Online support publishing group layers as hosted feature services?

Answer

When authoring a map in ArcMap or ArcGIS Pro to publish a hosted feature service, group layers can be used to organize layers in the Table Of Contents.

When the feature service is published to ArcGIS Online, these group layers are no longer seen in the layer structure.

ArcGIS Online currently does not support publishing group layers as feature services. During the publishing process, group layers in Table Of Contents are omitted. When the feature service is published, the layers under a group layer are listed individually, outside any group. This limitation is described in the warning messages returned when analyzing a document in the Service Editor window before publishing the feature service.

Note:
This limitation for publishing group layers as feature services also applies to services hosted in ArcGIS Server or ArcGIS Enterprise. Group layers are supported when publishing map services to ArcGIS Server or ArcGIS Enterprise.

Although publishing group layers to ArcGIS Online is not possible, it is possible to group the published individual layers in ArcGIS Online Map Viewer. Refer to ArcGIS Online: Create and manage group layers for more information.

Note:
This functionality is not available in ArcGIS Online Map Viewer Classic. Refer to ArcGIS Online: Get started with Map Viewer Classic and ArcGIS Online: Get started with Map Viewer for more information on the differences between Map Viewer Classic and Map Viewer.