The structural and magnetic properties of one atomic layer thin nanostructures of Ni deposited on fcc Fe monolayer stripes on Ir(111) have been studied by (spin-resolved) scanning tunneling microscopy measurements. Ni grows dominantly in fcc stacking on Ir(111), whereas it forms a dense reconstruction pattern on Fe/Ir(111), with bridge site dislocation lines separating triangularly shaped fcc and hcp regions. In the interior of the Ni nanostructures, fcc and hcp areas are of comparable size, but the fcc stacking dominates at the edges. The magnetic nanoskyrmion lattice of Fe/Ir(111) undergoes a transition to ferromagnetism where covered with a single layer of Ni. The Ni/Fe bilayer islands show an out-of-plane easy axis and can be switched by external magnetic fields of only 1.0 T–1.5 T.