Penelitian ini bertujuan untuk menganalisis pengaruh mobile banking interface design, mobile banking security assurance, dan mobile banking system quality terhadap mobile banking service quality yang membentuk customer loyalty pada pengguna BCA mobile di Kabupaten Sidoarjo. Penelitian ini dilakukan dengan jenis penelitian kausal dan pendekatan penelitian secara kuantitatif. Penelitian ini dilakukan terhadap masyarakat pengguna BCA mobile di Kabupaten Sidoarjo. Pengumpulan data dilakukan dengan mendistribusikan kuesioner kepada setiap konsumen. Teknik pengambilan sampel dilakukan secara snowball sampling. Kemudian teknik analisis yang dilakukan adalah structural equation modelling (SEM). Hasil penelitian membuktikan bahwa mobile banking interface design, mobile banking security assurance, dan mobile banking system quality berpengaruh positif signifikan terhadap mobile banking service quality. Hasil penelitian juga menjelaskan bahwa mobile banking service quality berpengaruh positif terhadap customer loyalty pengguna BCA mobile. Penelitian ini memberikan implikasi dalam bentuk strategi manajerial, yang menjelaskan bahwa pemahaman lebih lanjut terhadap faktor ini dapat membantu Bank BCA untuk meningkatkan loyalitas nasabah untuk menggunakan layanan perbankan melalui BCA Mobile / This study aims to analyze the influence of mobile banking interface design, mobile banking security assurance, and mobile banking system quality on mobile banking service quality that forms customer loyalty among BCA mobile users in Sidoarjo Regency. This research was conducted with a causal research type and a quantitative research approach. This research was conducted on BCA mobile users in Sidoarjo Regency. Data collection was carried out by distributing questionnaires to each consumer. The sampling technique was carried out by snowball sampling. Then the analysis technique used was structural equation modeling (SEM). The results of the study prove that mobile banking interface design, mobile banking security assurance, and mobile banking system quality have a significant positive effect on mobile banking service quality. The results of the study also explain that mobile banking service quality has a positive effect on the customer loyalty of BCA mobile users. This study provides implications in the form of managerial strategies, which explain that further understanding of this factor can help Bank BCA to increase customer loyalty in using banking services through BCA Mobile