Cincinnati promoted Spiers from Triple-A Louisville on Sunday.
Spiers will make his 2026 season debut when he is called on to pitch. In four games with Louisville this season, the 28-year-old owns a 3.54 ERA, 1.03 WHIP and 26:5 K:BB over 20.1 innings. The Reds designated TJ Friedl for assignment in order to make room for Spiers on both the 28- and 40-man rosters.