AbstractThis paper introduces an innovative three-piece boltless connection for assembly of volumetric building units or modules in multistory modular buildings. The proposed connection comprises a vertical connector and an independent horizontal connector. Overall development was targeted for steel and steel-hybrid modules of the corner-supported or selective bearing type, and on satisfying certain structural, constructional, and manufacturing performance requirements. The vertical connector makes use of a standard mechanism to enable fast, simple, safe, and remote operability, whereas the proposed horizontal connector uses a simple transfer plate. Details regarding the design of the connector and the experimental verification of its structural and functional performances are presented in this paper. Structural performance tests were conducted to verify key axial and shear characteristics, whereas functional performance tests were performed to assess the overall functionality after connector fabrication, test specimen fabrication, specific stages of loading, and during remote operation. The results highlight that the proposed connection satisfactorily meets its key expectations and can provide quantum improvements to the current modular construction industry for realizing fully modular buildings.