Angelique Kidjo, the Indigo Girls, MC Lyte, Amber Coffman, Mary Chapin Carpenter, Samantha Ronson and more will also perform at the Washington, D.C. march.
"I am honored to join this critical movement to bring justice and equality to all," Monae said in a statement. "Music has always been a powerful tool for galvanizing unity and I believe that singing and standing together, our voices will be stronger than any force that tries to repress us."
Maxwell added, "We are here because women are every bit as capable if not more able to pursue any goal they set forth for themselves. Were it not for the limitless depths of their love we would not be the men that we are."
Katy Perry, Scarlett Johansson, Amy Schumer and Cher also previously revealed they'd take part in the America Ferrera-led "Artist Table" for the march. Since that announcement, Questlove, Grimes, Neko Case, Rakim, TV on the Radio and more have also pledged to participate in sister marches nationwide.
"The Women's March on Washington aims to send a message to all levels of government and the incoming administration: that we stand together in solidarity and expect elected leaders to act to protect the rights of women, their families and their communities," organizers said in a statement.
Additionally, the National, Sleater-Kinney, Tig Notaro and more artists, celebrities and politicians will appear at the March on Washington's After Party supporting Planned Parenthood.
In a statement Wednesday, Beyonce also threw her support behind the march, which is expected to draw hundreds of thousands to Washington, D.C.
"Together with Chime for Change, we raise our voices as mothers, as artists, and as activists," she wrote. "As #GlobalCitizens, we can make our voices heard and turn awareness into meaningful action and positive change."