Background Blood flow-induced wall shear stress (WSS) is a strong local regulator of vascular remodeling, but its effects on arteriovenous fistula (AVF) remodeling are unclear. Methods In this prospective cohort study, we used statistical mixed-effects modeling to investigate the associations between WSS and AVF remodeling in 120 participants undergoing AVF creation surgery. Postoperative magnetic resonance imaging data at 1 day, 6 weeks, and 6 months were used to derive current WSS by computational fluid dynamic simulations and to quantify subsequent changes in AVF lumen cross-sectional area at 1-mm intervals along the proximal artery and AVF vein. Results Combining artery and vein data, prior mean WSS was significantly associated with lumen area expansion. Mean WSS at day 1 was significantly associated with lumen area change from day 1 to week 6 (11% larger week-6 area per IQR increase in day-1 mean WSS, 95% CI 5%-18%; n=101), and mean WSS at 6 weeks was significantly associated with lumen area change from week 6 to month 6 (14% larger area per IQR increase, 95% CI 3%-28%; n=52). The association of mean WSS at day 1 with lumen area expansion from day 1 to week 6 differed significantly by diabetes (p=0.009): 27% (95% CI 17%-37%) larger area per IQR increase in mean WSS without diabetes, and 9% (95% CI -1-19%) with diabetes. Day-1 oscillatory shear index (OSI) was significantly associated with lumen area change from day 1 to week 6 (5% smaller area per IQR increase in OSI, 95% CI 3%-7%), and OSI at week 6 was significantly associated with lumen change from week 6 to month 6 (7% smaller area per IQR increase in OSI, 95% CI 2%-11%). WSS spatial gradient was not significantly associated with subsequent remodeling. In a joint model, WSS and OSI statistically significantly interacted in their associations with lumen area expansion in a complex nonlinear fashion. Conclusion Higher WSS and lower OSI were associated with greater lumen expansion after AVF creation surgery.