The establishment of an estrogen receptor-positive (ER+) breast tumor model plays a crucial role in the preliminary screening of anticancer drugs and understanding disease mechanism. However, the construction of this model requires exogenous estrogen supplementation. The current method of estrogen supplementation was limited by its high cost and potential side effects. Herein, we utilized Poly D, L-lactic-co-glycolic acid (PLGA) as substrate to develop the estradiol valerate microneedle patch (EVMP). The EVMP exhibited excellent drug loading capacity (46 μg/needle) and good mechanical strength (>0.2 N/needle). Importantly, the EVMP exhibited favorable sustained release of estradiol valerate ability in vitro. Subsequently, the EVMP successfully achieved sustained release in Balb/c nude mice, resulting in an average MCF-7 (ER+) tumor volume of approximately 300 mm3 at day 35. In addition, no significant inflammatory reaction or urinary calculi were observed during this process, which further demonstrated the efficacy and safety of the EVMP. Overall, these findings suggested that the EVMP held great potential as a safe and animal-friendly alternative platform for constructing the ER + breast cancer model.