The Bronx-born rapper posted a picture of the pair to Instagram and said "Stay tuned," for a video they are collaborating on to educate voters.
She said she'll help fight for "economic, racial and social justice for all."
Sanders said it's part of an effort to get more young people to vote.
RodeoHouston performers who have paid tribute to the Queen of Tejano
Cardi B pays tribute to Selena at RodeoHouston and in 'Please Me' video