Abstract: A retractable blade utility knife is provided with storage for spare blades within the knife handle and a knife blade carrier that can be actuated to an operative position in a direction longitudinal to the knife housing, and to a knife blade loading position in a direction transverse to the knife housing, without disassembly of the knife housing. An externally accessible button extends from an L-shaped slot through a housing shell of the knife and allows for actuation of the knife blade carrier from a loading position to an operative position in one continuous motion. The externally accessible button is connected at its proximal end to a flexible arm on the blade carrier. The distal end of the flexible arm of the blade carrier has a transversely extending lip that selectively engages with longitudinally spaced notches on horizontal ribs extending from the inside surface of the knife housing shell.