The Just Dance hitmaker is teaming up with bosses at the Robin Hood Foundation to hand the generous donation to one of five New York City charities set up to help homeless youth.
The pop star has asked her devotees to vote for the organisation which most deserves the money in a poll on her Facebook page.
The winner, to be announced at a Robin Hood Foundation gala on 9 May (11), will receive $500,000 over a two-year period, while the other charities will receive smaller grants.
Gaga says, "I'm thrilled to be working with the Robin Hood Foundation to distribute funds to help the youth of New York City. NYC is my hometown and I think investing in these kids' future will go a long way."