Despite the dramatic antitumor efficiency of certain immune checkpoint inhibitors, immunotherapy has met a bottleneck regarding the response rate and resistance in cancer patients. Increasing evidence indicates that Wnt/β-catenin signaling, one of the best-characterized cancer drivers, promotes cancer progression by regulating the tumor-immune cycle in most of the nodes, including dendritic cells, T cells, and tumor cells. Specifically, abnormal Wnt/β-catenin signaling directly alters a number of regulators critical for the antitumor activities of T cells, especially effector T cells, T helper cells, and regulatory T cells. We propose that targeting Wnt/β-catenin signaling would potentially improve clinical outcomes of cancer patients by overcoming the primary, adaptive, and acquired resistance to immunotherapy.