The Dodgers and Astros begin the best-of-seven World Series with Game One in Los Angeles on Tuesday.
Dodgers manager Dave Roberts had expressed confidence that Seager would be fit to feature for the NL champions.
Shortstop Corey Seager and right-hander Brandon McCarthy were added to the active roster for the World Series by the Los Angeles Dodgers, who dropped outfielder Curtis Granderson and backup catcher Kyle Farmer.
Roberts has given Granderson's roster spot to pitcher Brandon McCarthy, who hasn't appeared in a game since October 1.
Roberts has said it's possible Seager will be used as a designated hitter on the road when the games shift to Houston on Friday.
Charlie Culberson did well while filling in for Seager during the NLCS.
Culberson is on the World Series roster too, and could see time in the infield and the outfield.
The Dodgers were hoping for a power surge out of Granderson, but he wasn't able to supply it.
McCarthy was 6-4 with a 3.98 ERA in 19 games (16 starts) during the regular season. Initially brought in to replace Pederson, Granderson had only 18 hits in 112 plate appearances for Los Agneles (.161) during the regular season, and has just one hit and eight strikeouts in his 15 postseason at-bats. He appeared in 20 regular-season games.
Farmer was a luxury, a right-handed hitting catcher who gave Roberts the flexibility of using Barnes and Grandal in the same game. In three relief appearances to end the season, he allowed four runs in six innings.
Clayton Kershaw will start Game 1, Rich Hill Game 2, Yu Darvish Game 3 and Alex Wood Game 4.