Seiring dengan berkembangnya teknologi yang pesat ditambah dengan adanya pandemi Covid-19, internet telah menjadi kebutuhan penting dalam kehidupan sehari-hari bagi masyarakat Indonesia dan juga menjadikan mobile banking seperti Mandiri mobile banking semakin populer karena efisiensinya. Penelitian ini dilakukan dengan tujuan untuk mengetahui pengaruh Reliability, Privacy and Security, Website Design, Customer Service and Support, dan Satisfaction terhadap Loyalty pada nasabah pengguna Mandiri mobile banking di kota Medan. Penelitian ini diharapkan agar dapat digunakan oleh peneliti di masa mendatang sebagai referensi dan diharapkan agar dapat digunakan oleh managemen Bank Mandiri dalam mengatur strategi pemasaaran melalui Reliability, Privacy and Security, Website Design, Customer Service and Support, dan Satisfaction terhadap Loyalty serta mengevaluasi strategi tersebut sesuai dengan hasil analisis dari penelitian yang telah dilakukan. Hasil penelitian ini diharapkan dapat menjadi referensi bagi Bank Mandiri untuk mempertimbangkan variabel-variabel yang ada sebagai kunci utama mendapatkan customer loyalty. Penelitian ini merupakan penelitian kausal dengan metode penelitian kuantitatif dengan pengolahan data menggunakan AMOS 22.0. Pengumpulan data melalui penyebaran kuesioner dengan mengumpulkan 125 responden yang merupakan nasbah pengguna Mandiri mobile banking di Medan. Hasil penelitian ini menunjukkan bahwa reliability, privacy and security, website design, dan customer service and support tidak berpengaruh signifikan terhadap loyalty; reliability, privacy and security, dan website design tidak berpengaruh signifikan terhadap satisfaction. Sedangkan customer service and support berpengaruh signifikan terhadap satisfaction; dan satisfaction berpengaruh signifikan terhadap loyalty./ Along with the rapid development of technology coupled with the Covid-19 pandemic, the internet has become an important necessity in everyday life for Indonesian people and has also made mobile banking such as Mandiri mobile banking increasingly popular because of its efficiency. This research is conducted with the aim of knowing the effect of Reliability, Privacy and Security, Website Design, Customer Service and Support, and Satisfaction on Loyalty of Mandiri mobile banking users in Medan. This research is expected to be used by researchers in the future as a reference and is expected to be used by the management of Bank Mandiri in managing marketing strategies through Reliability, Privacy and Security, Website Design, Customer Service and Support, and Satisfaction with Loyalty and evaluating these strategies accordingly. with the results of the analysis of the research that has been done. The results of this study are expected to be a reference for Bank Mandiri to consider the existing variables as the main key to getting customer loyalty. This research is a causal research. The research method used is a quantitative research method with data processing using AMOS 22.0. Collecting data through questionnaires by collecting 125 respondents from Mandiri mobile banking users in Medan. Results of this research shows that reliability, privacy and security, website design, and customer service and support have no signifikan effect towards loyalty; reliability, privacy and security, and website design have no significant effect towards satisfaction. While customer service and support has significant effect towards satisfaction; and satisfaction have significant effect towards loyalty.