She is currently racing for Rahal-Letterman Racing, posting fourth-place finishes in each of her last two races and ninth in the IRL overall points standings.
"I'm proud to be joining Andretti Green Racing next year," said Patrick. As loyal as I've been to Rahal-Letterman, I felt like it was time for a change and this is what's best for my future."
Patrick, 24, is in her second year racing on the IRL. She was the circuit's rookie of the year in 2005 when she finished 12th in the points standings. Her best finishes were a pair of fourth places, including at the Indianapolis 500.
Patrick's father had told a Chicago Tribune reporter this month that Patrick was considering a move to NASCAR.