Mobile payment (m-payment) platforms have revolutionized financial technology in Indonesia, particularly aiding the operations of UMKM (Micro, Small, and Medium Enterprises). Despite their growing adoption, retaining user loyalty remains a challenge. This study applies the Stimulus-Organism-Response (SOR) framework to investigate how perceived value and perceived security (stimuli) influence customer satisfaction and e-trust (organism), ultimately affecting customer loyalty (response). Data were collected from 75 MyBCA mobile payment users in Jakarta and analyzed using PLS-SEM. Results show that perceived value and security significantly impact satisfaction and e-trust, which in turn influence loyalty. However, perceived security does not directly influence loyalty but acts through satisfaction and trust. The findings offer valuable insights for fintech providers aiming to enhance user retention through strategic improvements in value and security. © 2025 IEEE.