Julien will start at designated hitter and bat eighth in Friday's opener in Miami.
The placement of Mickey Moniak (finger) on the 10-day injured list will free up some at-bats at DH and in the outfield for the Rockies. Julien will get the first crack at DH, though the spot is likely to be a revolving door. The 26-year-old was acquired from the Twins over the offseason.