For efficient cancer theranostics, surface modification of nanomaterials plays an important role in improving targeting ability and reducing the non-specific interactions with normal tissues. Recently, the biomimetic technology represented by coating of cancer cell membranes (CCMs) has been regarded as a promising method to strengthen the biocompatibility and targeting specificity of nanomaterials. Furthermore, the engineered CCMs (ECCMs) integrated with the natural biological properties of CCMs and specific functions from other cells or proteins have offered more possibilities in the field of cancer theranostics. Herein, the recent progresses in the design and preparation of ECCMs are summarized, and the applications of ECCMs in targeting delivery, activation of immunity, and detection of circulating tumor cells are reviewed. Finally, the current challenges and future perspectives with regard to the development of ECCMs are briefly discussed.