General manager Mike Rizzo announced the moves before Saturday's game against the San Francisco Giants.
Schierholtz, a .254 career hitter with 51 home runs and 224 RBIs in 776 games with the Cubs, Phillies and Giants, was signed to a minor league contract Aug. 18. He hit .192 with six homers in 99 games for Chicago before being designated for assignment Aug. 6.
The 30-year-old Schierholtz gives Washington a veteran left-handed bat off the bench to replace Nate McLouth, sidelined since Aug. 2.
McLouth had surgery on the torn labrum in his right shoulder Friday and was placed on the 60-day disabled list. He hit .173 with a homer and seven RBIs in 79 games.
Taylor was 3 for 18 (.167) with a homer in seven games during his first stint in the majors.