Cancer immunotherapy, mainly depending on the immune system, holds enormous potential in treating various cancers and received promising results. However, for most patients, their efficacy is greatly limited by the immunosuppressive barrier in the "cold" tumor microenvironment, resulting in a low response rate in the clinic. Thus, in recent decades, breaking the immunosuppressive barriers by engineered nanoplatforms (ENs) has proved to be a prospective strategy to solve the above issues for enhancing cancer immunotherapy. In this review, the authors summarize the characterizations of diverse immunosuppressive barriers and how ENs break them, focusing on the ENs design, potential modulation targets, and therapeutic strategies. It mainly includes: 1) converting poor immunogenicity by nano-adjuvant, 2) alleviating tumor fibrosis by nanoscavenger, and 3) reducing immunosuppressive factors by nanoregulator. Moreover, perspectives toward future directions and challenges are presented to understand further and accelerate the clinical translation of these ENs.