This study aims to investigate the factors influencing customer satisfaction in M-banking services in Vietnamese commercial banks, focusing on Sacombank’s Hanoi Branch. Based on the SERVQUAL model by Parasuraman et al. (1988) and related literature, this study identifies five critical factors that determine customer satisfaction: reliability, responsiveness, tangibility, assurance, and empathy. A survey was conducted with 208 retail customers at Sacombank Hanoi Branch who have used the M-banking services. Structural equation modeling was used to analyze the data, revealing that all five factors positively affect customer satisfaction. Furthermore, the study highlights the diminishing but significant impact of these factors on customer satisfaction. Based on the findings, specific recommendations and strategies are proposed for Sacombank’s Hanoi Branch and its head office to enhance customer satisfaction in M-banking services.