<p>Outdoor cultural relics are particularly vulnerable to deterioration from various environmental factors, with weathering being the most critical. This weathering process is primarily driven by the combined effects of moisture and salts. Besides, the expansion of freezing water within pores and the corrosive impacts of acid rain further accelerate the degradation process. Unlike traditional conservation methods, microbially induced carbonate precipitation (MICP) technology stands out for its environmental sustainability and compatibility with the original geomaterial substrates of cultural relics. Although recent studies have investigated the applications of MICP in geomaterial-based cultural relic preservation, a comprehensive evaluation connecting its advantages to the underlying weathering mechanisms remains limited. This review comprehensively examines the current state of MICP technology in cultural relic conservation, categorizing its applications into bioprotection and biorestoration. It provides an in-depth analysis of how MICP mitigates weathering effects and enhances weathering resistance of relics, based on a detailed discussion of weathering mechanisms. The review also summarizes improvements in material properties achieved through MICP, in terms of both mitigating weathering effects and enhancing weathering resistance. Furthermore, current limitations and practical challenges hindering its applications especially in large-scale level are also discussed. Overall, this review highlights the advantages and applicability of MICP technology as a sustainable and effective approach for preserving weathered earthen and stone relics, offering valuable insights to guide future development and implementation in cultural relic conservation.</p>