Abstract: A handheld safety knife is disclosed herein which comprises a removable blade cartridge installed into a handle having a cartridge recess. The cartridge recess retains the blade cartridge within the handle through one or more of the following: a contoured side wall matching that of the removable blade cartridge; a plurality of anti-rotation protrusions which are located in the cartridge recess; or a cartridge orientation feature which mates with a cavity located in the removable blade cartridge. When the blade becomes used, it may be removed and reoriented to access a fresh blade. During this blade exchange, the cartridge may be removed from the handle, but the blade is not exposed, thus yielding a safer design over that taught in the prior art.