Various examples of magnetic integration of matrix transformers with controllable leakage inductance are described. In one example, a transformer includes a magnetic core comprising a plurality of core legs and a leakage core leg. The leakage core leg is positioned among the plurality of core legs to control a leakage inductance of the transformer. The transformer also includes a planar winding structure. The planar winding structure includes a primary winding and a plurality of secondary windings. The primary winding and the plurality of secondary windings extend in a number of turns around the plurality of core legs, without a turn around the leakage core leg, to further control the leakage inductance of the matrix transformer.