The present disclosure discloses a lateral rotary positioning mechanism arranged between a base and a body, the base is rotatably arranged on the body and includes an engaging pin and an engaging recess, the engaging pin is telescopically arranged on the body, the engaging recess is arranged on a bottom surface of the base and at least one side of the base in a lateral direction, and when the base is rotated to a lateral direction with respect to the body, the engaging pin is inserted into the engaging recess to limit rotation of the base. The lateral rotary positioning mechanism capable of being rotatable to a lateral direction to position the carrier of the present disclosure has advantages of a simple structure and capability of improving the use convenience and safety of the child carrier. In addition, the present disclosure also discloses a child carrier.