The Mariners activated Ferrer from the paternity leave list Thursday.
Ferrer missed the first three games of the series against the Astros as he welcomed a new baby to the family, but he'll be available for Thursday's finale. The hard-throwing southpaw has been terrific in his first season as a setup man in Seattle, boasting a 1.80 ERA and 16:3 K:BB over 20 innings.