Gray is expected to join his new team Saturday. He had to pass through waivers after the White Sox designated him for assignment, which is where the Mariners made the claim.
Working in long relief, Gray was a pleasant surprise for the White Sox, who signed him as a free agent this offseason. He did not make the Opening Day roster out of spring training, but was recalled after the first week when the pitching staff was expanded to 12 members.
In six outings, Gray posted a 2.70 ERA, closing out his stay with the White Sox with three scoreless innings of relief Tuesday against the Angels. He had just one rocky outing, when he gave up three runs to the Yankees on April 28.