Bring a large pot of lightly salted water to a boil. Cook mostaccioli at a boil until cooked through yet firm to the bite, about 11 minutes; drain.
Cook and stir ground beef in a large pot over medium-high heat until crumbly, evenly browned, and no longer pink, 5 to 7 minutes. Drain and discard any excess grease.
Add picante sauce and stewed tomatoes to the ground beef; cook, stirring occasionally, until the tomatoes soften completely, about 10 minutes. Gently stir the cooked mostaccioli into the ground beef mixture. Add Mexican-style cheese; cook and stir until the cheese is melted, about 5 minutes.