Anaplastic thyroid carcinoma (ATC) is a lethal malignancy with a 1 year survival rate of less than 20%. Combination chemotherapy with cisplatin and paclitaxel is recommended as a critical therapeutic approach toward ATC. However, harsh side-effects on patients and unsatisfactory intratumoral concentrations hamper the effectiveness of systemic chemotherapy. In this work, an in situ spontaneously forming micelle-hydrogel system (iMHS) with programmable-release characteristics was developed for sequential chemotherapy. Taking advantage of the diffusion rate of the hydrophobic drug in the micellar network and the degradation of the hydrogel matrix, iMHS supported sequential chemotherapy via programmatic release. Moreover, in vitro and in vivo studies demonstrated the superiority of sequential release from iMHS over other approaches, regardless of the genetic profile (e.g., different BRAF, TP53, and TERT promoter mutations, etc.). Additionally, iMHS presented the significant ability to prevent local tumor recurrence in a post-surgical model. Overall, iMHS may serve as a promising strategy for the enhanced localized treatment of ATC via the programmable release of chemotherapy drugs with implied translational value.