We report a new route of defect engineering on the nanoscale. For elemental Ni, nanoscale domains (average 7 nm in diameter) were produced during electro-deposition, occupying only ~2.4% of the total volume. Yet the resulting Ni achieves a yield strength approaching 1.3 GPa, on par with the strength previously reported for nanocrystalline Ni with uniform grains. Simultaneously the material exhibits a uniform elongation as large as ~30% in uniaxial tension, close to the hallmark ductility of ductile metals. Electron microscopy observations and molecular dynamics simulations demonstrate that the spread-out nanoscale domains effectively block dislocations, akin to the role of precipitates for Orowan hardening in alloys. In the meantime, the abundant domain boundaries provide effective dislocation trapping for efficient dislocation multiplication and storage in the grain interior to sustain a pronounced strain hardening rate to large uniform elongations.