Due to the advantages of large surface area, easy functional structure, good biocompatibility, and easy integration into signal transduction system, hydrogel-based nanocomposite is an excellent electrode modification material. Several common synthesis strategies of hydrogel-based nanocomposites and their significance as electrochemical modified electrode materials were summarized in this paper. The preparation of hydrogel-based nanocomposites modified electrode and their sensing mechanism for the electrochemical detection were discussed. Finally, the preparation of hydrogel-based nanocomposites and their applications in electrochemical sensors are summarized and prospected, which will have importance to promote the development of electrochemical sensing detection technology.