This study examines the effect of digital technology adoption on MSME sustainability and evaluates business model innovation as a mediating mechanism in Sumbawa Regency, West Nusa Tenggara. A quantitative explanatory design was applied to 100 owners or principal managers selected from a population of 1,359 MSMEs using the Slovin formula and purposive criteria. Digital technology adoption, business model innovation, and MSME sustainability were measured reflectively through twelve items on a four-point Likert scale and analysed with Partial Least Squares Structural Equation Modeling in SmartPLS 4 using 5,000 bootstrap subsamples. The results show that digital technology adoption positively affects business model innovation (β = 0.582; t = 7.559; p < 0.001) and directly improves MSME sustainability (β = 0.269; t = 3.318; p = 0.001). Business model innovation also has a positive effect on sustainability (β = 0.545; t = 6.478; p < 0.001). The indirect effect is significant (β = 0.318; t = 4.864; p < 0.001), indicating complementary partial mediation. The model explains 33.9% of business model innovation and 54.1% of MSME sustainability. The findings underline that digital tools generate durable economic, social, and environmental benefits when MSMEs redesign value propositions, customer interfaces, operating processes, and revenue mechanisms rather than merely adding isolated applications.