Ferguson was recalled from Triple-A Oklahoma City on Thursday.
The 25-year-old posted a 7.36 ERA and 1.97 WHIP in 7.1 innings over 10 appearances (two starts) in Oklahoma City to begin the year, but he'll join the Dodgers' bullpen after Michael Grove was sent down. Ferguson made a relief appearance for the major-league club in mid-May and struck out one in a scoreless inning. He should pitch mainly in low-leverage situations.