Ubiquitin-specific protease 10 (USP10) has emerged as a pivotal yet paradoxical regulator in breast cancer (BC) pathogenesis, exhibiting context-dependent duality as both an oncogenic driver and tumor suppressor. This review synthesizes recent advances in elucidating USP10's mechanistic roles in modulating oncogenic signaling, tumor immunity, and therapeutic resistance, with a central focus on its paradoxical dual regulation. USP10 stabilizes tumor-promoting substrates to drive the malignant phenotypes, while also exerting tumor-suppressive effects. Clinically, USP10 overexpression correlates with aggressive phenotypes and poor prognosis. Therapeutically, USP10 inhibition synergizes with Poly ADP-ribose polymerase (PARP) inhibitors and antibody-drug conjugates (ADCs), effectively suppressing tumor growth in preclinical models. Key challenges include resolving USP10's functional dichotomy across BC subtypes, developing isoform-selective inhibitors, and overcoming resistance mechanisms. Future directions emphasize spatial proteomics to map USP10 interactomes in metastatic niches and genetically engineered models for validating synthetic lethality approaches. Collectively, USP10 represents a promising therapeutic target in BC. Its complex, context-dependent role underscores the need for targeted strategies to exploit its functions for precision oncology.