A combined fan-compressor impeller comprises a single hub and a plurality of spaced main blades extending outwardly from the hub such that an air passage channel is defined between two of the main blades. Each of the main blades is a mixed flow blade which continuously extends from a fan section at an inlet end of a channel to a compressor section at an outlet end of the channel without any axial clearance between the fan section and the compressor section, providing aerodynamic matching of pressurized air flowing through the channel from the fan section to the compressor section.