We report a synthesis of colloidal nanostructures combining a magnetic material (FePt) with a narrow-gap semiconductor (PbS and PbSe) in form of core shells or nanodumbbells and explore their optical, magnetic, electrical, and magnetotransport properties. The arrays of "magnet-in-the-semiconductor nanostructures show semiconductor-type transport properties with magnetoresistance typical for magnetic tunnel junctions, thus combining the advantages of both functional components. We observed gate-controlled charge transport through the arrays of FePt PbS and FePt PbSe core shell nanostructures with an electron mobility of 0.01 cm(2)/(V s) and 0.08 cm(2)/(V s), respectively, combined with ferro- and superparamagnetic behavior and large tunneling magnetoresistance. This work shows that multicomponent colloidal nanostructures can be used as the building blocks for design of multifunctional materials for electronics and optoelectronics.