Seattle acquired Bolton from the Pirates on Thursday in exchange for cash considerations.
Bolton surrendered 15 earned runs on 30 hits and 15 walks over his first 21.1 major-league innings with Pittsburgh in 2023, but the 25-year-old right-hander owns a 3.38 ERA with 129 strikeouts in 122.1 career innings of work at the Triple-A level. He could prove to be a nice pickup for the Mariners if his command improves.