The Royals released Jackson on Tuesday.
Jackson signed a minor-league deal with Kansas City last month and appeared in 10 games with Triple-A Omaha, where he registered a 5.27 ERA, 1.39 WHIP and 16:4 K:BB across 13.2 innings. The 34-year-old hasn't pitched in the big leagues this season after suiting up for three teams in 2025.