The rapid increase of mobile data subscribers and deployment of broadband radio access networks push mobile operators to upgrade their mobile backhaul from expensive legacy TDM transport to carrier Ethernet for cheaper operational expenditures. The Metro Ethernet Forum has defined a set of Ethernet Virtual Connection services that are adopted to provide scalable Ethernet transport for mobile backhaul. However, these services usually address single cell site backhaul per UNI handoff, neither considering statistical multiplexing gain at a hub site which aggregates backhaul traffics of multiple cell sites, nor supporting Quality-of-Service provisioning in overbooked backhaul pipe. This paper proposed an efficient carrier Ethernet overbooking solution for mobile backhaul. A statistical estimation method has been developed for deriving a safe overbooking factor at a given UNI. Then two efficient transport architectures were proposed to support bandwidth sharing in cellular cluster with overbooked backhaul bandwidth in carrier Ethernet. A novel bandwidth control algorithm has been derived at customer edge device to provide Quality-of-Service for multimedia traffics over overbooked UNI, with SLA policing and protection on high priority services. Experimental data analysis and simulations have showed that our new schemes can benefit mobile operators in resource utilization efficiency, carrier Ethernet cost saving and backhaul performance.