Rational cobalt phosphide/carbon (CoP/C) complex film composed of densely assembled CoP-in-carbon nanosheets was successfully constructed via filtration-induced self-assembly and in-situ transformation strategy. The successful implementation of this method relies on the morphology controlled preparation of graphene-like Co alkoxide by varying the chain length of polyols to regulate the polycondensation process. The graphene-like CoP-in-carbon construction units can accelerate ions/electrons transportation and guarantee structural robustness. Thanks to its ideal composite structure, CoP/C complex film exhibits outstanding cycling and rate performances, including high capacities up to 920.5 mAh g−1 over 200 cycles at 1 A g−1 and 826.5/662.3 mAh g−1 after cycling under 2/4 A g−1 over 1000 cycles. Besides, full-cells constructed with CoP/C complex film anodes and LiCoO2 cathodes exhibit superior cycling stability and reliable capacities of 773.4/518.7 mAh g−1 after 200 cycles at high rates of 1/4 A g−1. Such efficient and reliable strategy can offer new insights and understanding about the construction of advanced film materials for energy-storage devices.