Pseudomyxoma peritonei (PMP) is a neoplastic disease characterized by intraperitoneal mucin accumulation and redistribution. Accurate preoperative assessment of disease distribution, the peritoneal cancer index (PCI), and the feasibility of complete cytoreduction is crucial for treatment planning and prognostic evaluation. Although contrast-enhanced CT remains the current first-line imaging modality, it has limitations in detecting small-volume lesions and evaluating lesions in anatomically complex regions. Owing to its multiparametric imaging capability and excellent soft-tissue contrast, magnetic resonance imaging (MRI) can better characterize lesions through T1-weighted imaging, T2-weighted imaging, diffusion-weighted imaging, dynamic contrast-enhanced imaging, and 5 - 10 min delayed contrast-enhanced imaging. MRI has shown important value in identifying the primary tumor, predicting pathological grade, assessing PCI, evaluating resectability, and monitoring postoperative recurrence. This review systematically summarizes the technical essentials and imaging features of multimodal MRI in PMP and discusses its clinical value in diagnosis, preoperative staging, treatment decision-making, and follow-up monitoring. It also highlights that the current application of MRI in PMP still faces challenges, including the lack of standardized scanning protocols and limited high-quality evidence. In the future, with the development of structured reporting, multicenter prospective studies, radiomics, and artificial intelligence, MRI is expected to further evolve from qualitative description to quantitative assessment and decision support, providing a more solid imaging basis for precision diagnosis and treatment of PMP.