The move was announced Tuesday by Ganassi, who also signed a multiyear extension with Target for both his open-wheel and NASCAR programs.
Franchitti won the 2007 IndyCar Series championship and the Indianapolis 500, but left open wheel for NASCAR at the end of the season to drive Ganassi's No. 40 Dodge in the Sprint Cup Series.
Ganassi never secured sponsorship for that team, and was forced to shutter it in July because of the weakening economy. Franchitti has lingered in NASCAR since, running a handful of second-tier Nationwide Series races as he and Ganassi tried to figure out his future.
Franchitti had said at the time his team closed that returning to IndyCar was not an option, but apparently changed his mind when Ganassi and Wheldon decided to part ways.
"I have always admired his competitive spirit when he raced against us and have really grown to see more of what he is about this season while he raced in NASCAR," Ganassi said. "When there was a possibility of an opening on our IndyCar team, the only person I thought about was Dario. This is going to be a great move for Dario and for our team.
Franchitti will join Scott Dixon, the reigning Indy 500 winner who is poised to wrap up his second IndyCar title, on Ganassi's open wheel team. Franchitti beat Dixon for the title a year ago, right before he announced he was joining Ganassi's NASCAR operation.
Franchitti likely had several opportunities with Ganassi -- including a Nationwide ride in NASCAR, and possibly a job in the Grand-Am Series -- but was intrigued by the recent unification of the IndyCar Series and the now-defunct Champ Car Series.
"Part of the reason that I signed with Ganassi last year was because of how many options that Chip has at his disposal for a driver. You can do almost any form of racing that you want," Franchitti said. "With unification and the new schedule having more road and street courses it made me think about this more and more.
"I have really enjoyed this last season in stock cars and have not completely closed that chapter of my professional career, but the opportunity that arose was just something I could not pass up."
Franchitti raced in just 10 Cup events this season. He missed five with a broken foot suffered in a crash at Talladega, and the No. 40 car fell outside the top 35 in points and failed to qualify for a handful of races before Ganassi finally closed it down.
Franchitti's highest finish was a 22nd at Martinsville in March. He's been better in the Nationwide car, with a career-best finish of fifth on the road course at Watkins Glen and a 13th and 11th in his last two outings.
Shortly after Franchitti's announcement, Panther Racing said Wheldon will return to the IndyCar team with which he began his IndyCar career in 2002.
Wheldon, who joined the Ganassi team in 2006, right after winning the series championship and the Indy 500 for Andretti Green Racing, has been overshadowed by Dixon in his time there.
"Dan Wheldon has done everything this organization has asked of him," Gansassi said. "He was competitive from the moment that he stepped into the car for us. Dan is a class act both on and off the track and we wish him nothing but the best."
Wheldon, who signed a multiyear agreement with Panther, said, "I'm looking forward to when my obligations with my current team have been honored, so I can get with the entire Panther family and start moving towards all of our goals of winning races and championships together. It's great to be back."
The championship will be decided this weekend at Chicagoland, where Dixon will try to hold off Helio Castroneves for the championship. The IndyCar teams also will race in non-points event at Surfers Paradise in Queensland, Australia on Oct. 26.
"I will certainly miss my working relationship with Scott Dixon and wish him and the team all the best for this weekend at Chicagoland," said Wheldon, who is fourth in the season points with wins at Kansas Speedway and Iowa Speedway.
All the movement comes at a tumultuous time for Ganassi, who has gone from three teams to two in NASCAR and is losing Cup driver Reed Sorenson at the end of the season. He still must fill that seat.
Also, sponsor Texaco is leaving Juan Pablo Montoya's NASCAR car at the end of the year.
At the same time, Ganassi's Grand-Am duo of Scott Pruett and Memo Rojas has already clinched the 2008 Daytona Prototype championship and Dixon needs only to finish ninth or better to wrap up his second IndyCar title.
Longtime partner Target remains committed to the organization, and its new contract ensures the sponsor and Ganassi will enter their 20th season together next year.
"We are excited about our relationship ... and we look forward to celebrating our 20th year with the team in 2009," said Target CEO Gregg Steinhafel. "This program has had tremendous success over the years, and we look forward to even more success in the years to come."
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AP Auto Racing Writer Mike Harris contributed to this report
Wheldon steps out of car, onto field
Franchitti will meet with Ganassi
