Broadcasting plays a fundamental role in transmitting a message from the sender to the rest of the network nodes in Mobile Ad hoc Networks (MANETs). The blind flooding scheme causes a broadcast storm problem, which leads to significant network performance degradation. In order to solve the problem, a dynamic probabilistic broadcasting scheme cross-layer design for MANETs (DPBSC) is proposed. DPBSC adopts the cross-layer design, which lets routing layer share the received signal power information at MAC layer while still maintaining separation between the two layers. The additional transmission range that can benefit from rebroadcast is calculated according to the received signal power, which is applied to dynamically adjust the rebroadcast probability. DPBSC reduces the redundant retransmission and the chance of the contention and collision in the networks. Simulation results reveal that the DPBSC achieves better performance in terms of the saved-rebroadcast, the average packet drop fraction, the average number of collisions and average end-to-end delay at expense of the throughput, which is respectively compared with the blind flooding and fixed probabilistic flooding applied at the routing layer while IEEE 802.11 at the MAC layer.