Ramirez, who was traded by Seattle to Tampa Bay on March 31, 2015, is under team control through the 2019 season.
"Erasmo brings us a good combination of experience, versatility and control as we look to both be better in 2017, and in future seasons," Mariners general manager Jerry Dipoto said in a statement. "We've added depth to our pitching staff in a variety of ways and maintained flexibility as we move forward with a player that is under club control for 2017, 2018 and 2019."
Ramirez, 27, was 4-3 with one save, six holds and a 4.80 ERA over 69 1/3 innings with 55 strikeouts in 26 games, including eight starts, for the Rays this season. As a reliever, he posted a 3.23 ERA over 30 2/3 innings with 23 strikeouts in 18 appearances, while limiting opponents to a .189 average with a .232 on-base percentage.
In six major league seasons with Seattle (2012-14) and Tampa Bay (2015-17), Ramirez is 29-32 with three saves and a 4.23 ERA over 530 innings with 409 strikeouts in 171 games, including 71 starts.
Cishek, 31, was 1-1 with one save and a 3.15 ERA over 20 innings with 15 strikeouts in 23 relief appearances this seasons for the Mariners since being activated from 10-day disabled list. He began the season on the 10-day DL on March 31 as he was recovering from surgery to repair a left hip labrum tear.
Since being signed by Seattle as a free agent on Dec. 14, 2015, Cishek was 5-7 with a 2.89 ERA over 84 innings with 91 strikeouts in 85 relief appearances.
In parts of eight major league seasons with Miami (2010-15), St. Louis (2015) and Seattle (2016-17), Cishek is 22-27 with 121 saves and a 2.83 ERA over 397 innings with 423 strikeouts in 396 relief appearances.