Cancer vaccines mount specific immune memory responses and hold great potential in suppressing postoperative colorectal cancer (CRC) recurrence. However, undesired lymph node trafficking and antigen cross-presentation hamper clinical translation of nanovaccines. Here, we propose a controllable transformable nanovaccine grounded on thermal fusion feature of liquid metal (LM) nanoparticles against postoperative CRC recurrence. After draining to lymph nodes, LM-based nanovaccines (LMVs) aggregate and transform from spheres to fusiform sharp under NIR irradiation, conducive to cytoplasmic delivery of LMVs and subsequent antigen cross-presentation. Benefitting from the morphology transformation, LMVs prolong the retention of loaded vaccine molecules in lymph nodes, resulting in satisfactory dendritic cell (DC) recognition and maturation. Such dual effects of transformable LMVs efficiently activate DCs and cytotoxic CD8 T cells, mediating strong systemic immune responses against local recurrence. Moreover, the transformable LMVs can induce potent specific immune memory, which is pivotal for eradicating metachronous liver and lung metastasis. This study provides a newly NIR light-regulated postoperative CRC prevention approach.