This study characterizes the population pharmacokinetics (PK) of vedolizumab in adults undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) for graft-versus-host disease (GvHD) prophylaxis. The analysis identified body weight and albumin levels as significant predictors of vedolizumab clearance, though the covariates studied had no clinically meaningful effect on its overall PK. The findings offer important insights into dosing strategies for vedolizumab in this patient population.