The Mariners selected Anderson's contract from Double-A Arkansas ahead of his start Saturday against the Cubs.
After turning in a 1.06 ERA and 0.64 WHIP while striking out 135 batters in 93.1 innings at Double-A, Anderson will skip past Triple-A and make his MLB debut Saturday. The 22-year-old lefty is viewed by many as the top pitching prospect in the sport and is likely to remain in the Mariners' rotation through the end of the season, assuming he doesn't struggle mightily during his first few major-league outings. Jhonathan Diaz was designated for assignment in a corresponding move.