There is provided a seat anti-theft assembly for use with a bicycle frame, the seat anti-theft assembly comprising a sleeve having a closed end, an open end and a sleeve chamber extending therebetween, the sleeve being mounted to the bicycle frame; a seat post having a seat end configured for receiving a seat thereon and an opposed engaging end adapted for engaging the sleeve chamber through the open end; a compartment mounted to the bicycle frame, the compartment having therein a compartment cavity in communication with a hollow lower portion of the bicycle frame, the compartment further having an access opening therein sized and shaped to allow access to the compartment cavity; a first stopping member mounted in the sleeve chamber; and a second stopping member associated with the seat post, the second stopping member being configured for cooperating with the first stopping member to allow slidable movement of the seat post along a restricted path of travel.