Keuchel, 34, was 2-5 with a 7.88 ERA this season after compiling a 5.28 ERA in 32 games last year. After signing a three-year, $55.5 million deal with the White Sox before the 2020 season, he finished fifth in Cy Young voting with a 1.99 ERA.
The White Sox don't have much room in their rotation when all their arms are healthy. Veteran Johnny Cueto has pitched well in his return to the majors, while righty Lance Lynn is close to returning from a knee injury that has sidelined him since spring training.
The White Sox have 10 days to trade Keuchel unless he's claimed on waivers. He's owed $14,456,044 for the remainder of his contract: $12,956,044 in salary for the rest of this season, plus a $1.5 million buyout of his 2023 option.
If he is released, another team could sign him for a prorated share of the $700,000 minimum, with the White Sox responsible for the rest.
The team recalled infielder Danny Mendick from Triple-A Charlotte to take Keuchel's spot on the roster.
Keuchel broke into the majors in 2012 with Houston. He won the AL Cy Young Award in 2015, going 20-8 with a 2.48 ERA in 33 starts for the Astros.
He is 101-87 with a 3.86 ERA in 262 career games, including 251 starts.
The Associated Press contributed to this report.