Schafer is in the starting lineup for the opener of a three-game series at Cincinnati, batting eighth and playing left field. Friday's start was his first in exactly a month, since June 4 at Minnesota.
He replaces utilityman Elian Herrera, who was optioned to Nashville on Thursday.
Schafer opened the season with the Brewers, hitting .190 in 37 games, including 20 starts. He was optioned to Nashville on June 13 and hit .235 with six RBIs in in 18 games.