Colbrunn, 33, missed 17 games with a strained right oblique muscle. He has not played since June 8, when he had two hits in the second game of a doubleheader sweep of the New York Mets.
After going 2-for-16 in April, he had 11 hits in his next 31 at-bats to raise his average to .277 with two home runs and five RBI in 19 games.
"I suspect he'll get some DH time and will get some days at first base," said Manager Bob Melvin. "I need to get him in more. He'll get more at-bats in the second half."
To clear a roster spot, the Mariners optioned infielder Luis Ugueto to Double-A San Antonio of the Texas League.
Ugueto, recalled when Colbrunn went on the DL, went 0-for-1 with a stolen base and a run scored in three games with Seattle.