Reversible martensitic transformation in shape memory alloys (SMAs) leads to well-known shape memory and superelasticity effects. Recently, we have achieved a number of new and unique functionalities in these materials by engineering microstructure, crystallographic texture, level of structural disorder, and their interactions with martensitic transformation. Alloys with tunable thermal expansion coefficients were created through crystallographic texturing by thermo-mechanical processing. This enables Invar effect and negative thermal expansion in a very wide temperature range. Strain glass and spin glass behaviors were observed in the same magnetic SMA by controlling the martensitic transformation and its frustration through changing structural disorder. We demonstrated that thermal and electrical conductivity can change significantly and reversibly upon martensitic transformation, which opens opportunities in thermal logic device applications. These examples show that reversible martensitic phase transformation can be used as an engineering tool to tailor the properties of materials as a versatile method to create “designer” materials.