Patrick, 29, told a news conference in Scottsdale, Ariz., she will be racing in the No. 7 GoDaddy.com Chevrolet for JR Motorsports, co-owned by Dale Earnhardt Jr., for the Nationwide series. Her number and car number for Tony Stewart's Sprint Cup team have yet to be determined.
"I'm just excited to finally say it," an enthusiastic Patrick said. "I'm sure there will be plenty of journalists out there that will be glad they don't have to ask the question anymore and plenty of other people that will be happy to stop speculating."
It was unclear whether she will race in the 2012 Daytona 500, but Patrick said she hopes to run a full Sprint Cup schedule in 2013.
"Daytona has a lot to offer as it relates to media exposure and I'm sure they will consider those factors," Daytona 500 President Joie Chitwood told the Sentinel. "If she attempts to run the Daytona 500 it will be good for her, good for Daytona, good for the sport. I will anxiously await her decision."
Patrick started her career in kart racing and later raced Formula Ford in England. In 2005, she broke into IndyCars, placing third in the Indianapolis 500 in 2009 and winning the Indy Japan 300 in 2008. She began dabbling in NASCAR last year.
It was unclear if she planned to run the 2012 Indy 500.
"I'll miss some of the venues and the people" in IndyCar, she said.
Patrick's next scheduled Nationwide race is Sept. 9 at Richmond, Va.