In 2008 Lowe set career-highs in games (57), innings (63.2), and strikeouts (55).
Among Mariners relievers, he ranked second in games, third in innings and third in strikeouts.
He was 0–2, with a 3.60 ERA at home, the 6th-lowest home ERA by a reliever in the American League.
He began the season by making 12 scoreless relief appearances in his first 13 games.
Lowe recorded a 0.55 ERA by allowing just one run in 16.1 innings from March 31 to June 13.
He tossed at least 2 innings in 12 of his 57 appearances.

He recorded his first Major League save April 11 against the Los Angeles Angels.
Lowe was optioned to Tacoma on August 25, but did not make an appearance.
He was recalled on September 2.
In 2008 Lowe set career-highs in games (57), innings (63.2), and strikeouts (55). Among Mariners relievers, he ranked second in games, third in innings and third in strikeouts. He was 0–2, with a 3.60 ERA at home, the 6th-lowest home ERA by a reliever in the American League. He began the season by making 12 scoreless relief appearances in his first 13 games. Lowe recorded a 0.55 ERA by allowing just one run in 16.1 innings from March 31 to June 13. He tossed at least 2 innings in 12 of his 57 appearances.
He recorded his first Major League save April 11 against the Los Angeles Angels. Lowe was optioned to Tacoma on August 25, but did not make an appearance. He was recalled on September 2.
Mark Lowe