A locking carabiner having an eccentric pivot that when rotated causes a reciprocating motion that moves the opening end of the gate into or out of locking engagement with the carabiner body. Rotation of the eccentric is controlled by a short lever that can be easily moved by a fingertip, consequently the gate can be conveniently manipulated and locked with the fingers of one hand. The locking mechanism adds negligible weight and bulk to the carabiner. The locking mechanism can be incorporated on bent gate, straight gate and wire gate carabiners.