A steering and leaning system for a vehicle includes a steering unit, a driving unit, and a control unit, each of which is adapted to be mounted to a main body of a vehicle. The driving unit is mounted between two spaced-apart front wheels of the main body, and includes an adjusting member that is driven swingably by the steering unit for controlling a moving direction of the vehicle. The control unit includes a control member that is connected movably to the adjusting member such that the swing movement of the adjusting member drives the main body to lean. The control unit is telescopically adjustable to be connected to different height positions on the adjusting member, thereby adjusting a lean angle of the main body.