This study investigates the development of an ultrastrong, deformable aluminum alloy with nanoscale intermetallics through selective laser melting (SLM). The alloy, Al92Ti2Fe2Co2Ni2, exhibits a combination of high strength (over 700 MPa) and significant plastic deformability. Heterogeneous nanoscale medium-entropy intermetallic lamellae form in the as-printed alloy, leading to a complex microstructure. Macroscale compression tests show high strength and plasticity, with flow stresses exceeding 900 MPa in certain regions. Micropillar compression tests reveal significant back stress and uniform deformation across the matrix and intermetallic phases. Post-deformation analyses indicate abundant dislocation activities and complex dislocation structures in the monoclinic Al9(Fe,Co,Ni)2 intermetallics. This study demonstrates that the introduction of heterogeneous microstructures and nanoscale intermetallics can effectively enhance the mechanical properties of additively manufactured aluminum alloys, offering a promising approach for designing ultrastrong and deformable materials.This study investigates the development of an ultrastrong, deformable aluminum alloy with nanoscale intermetallics through selective laser melting (SLM). The alloy, Al92Ti2Fe2Co2Ni2, exhibits a combination of high strength (over 700 MPa) and significant plastic deformability. Heterogeneous nanoscale medium-entropy intermetallic lamellae form in the as-printed alloy, leading to a complex microstructure. Macroscale compression tests show high strength and plasticity, with flow stresses exceeding 900 MPa in certain regions. Micropillar compression tests reveal significant back stress and uniform deformation across the matrix and intermetallic phases. Post-deformation analyses indicate abundant dislocation activities and complex dislocation structures in the monoclinic Al9(Fe,Co,Ni)2 intermetallics. This study demonstrates that the introduction of heterogeneous microstructures and nanoscale intermetallics can effectively enhance the mechanical properties of additively manufactured aluminum alloys, offering a promising approach for designing ultrastrong and deformable materials.