She and her brother Jake filmed a commercial for Rock the Vote, and visited the University of Southern California (USC) campus to encourage students to vote in the 2004 U.S. presidential election, in which she supported John Kerry.
Maggie Gyllenhaal je tudi sodelovala pri kampaniji »Ustvarjalci, združeni za zmago brez vojne«, s katero je začel Robert Greenwald in katere cilj je bilo delovati proti vojni v Iraku.