Abstract Low-temperature stress-induced martensite ageing at 400 K under a compressive stress of −500 MPa was applied along the [110]B2||[100]L10-direction for improving the functional properties of ferromagnetic Co35Ni35Al30 single crystals, which feature a B2-L10 martensitic transformation. Along the [001]B2-direction the stress-induced martensite aged crystals demonstrated a two-way shape memory effect with a giant reversible tensile strain of up to +7.3 (±0.3) % and a high functional stability during stress-free cooling/heating cycles. In addition, a rubber-like behavior with a reversible compressive strain of up to −4.4 (±0.3) % in loading/unloading cycles in the L10-martensite was observed.