Ryan Briscoe will replace NASCAR-bound Sam Hornish Jr at Penske Racing next year, the team have confirmed.
The Australian had been tipped to fill the slot left by the 2006 champion earlier this year, after racing with Penske in the American Le Mans Series, and his impressive performance in the Indianapolis 500.
The 26-year-old last raced in the series full-time in 2005, where his season with Chip Ganassi Racing was cut short by a big accident at Chicagoland.
"The IndyCar Series is where I really wanted to be next year," he said. "I'm just so excited about having a second chance.
"I definitely feel I have unfinished business after 2005. Coming back to Indy this year was a great step forward and I want to build on that."
While Hornish had been expected to switch to NASCAR, the move was only confirmed last week, but Briscoe was happy to play a waiting game.
"I've been under Penske's eye for a while with the ALMS programme and I've been closely watched," he added.
"If Sam wasn't going to NASCAR, I would have done all I could to be patient and remain on the team.
"I know the history Penske has, it is an amazing feeling and I want to make the most of it."
Team boss Roger Penske added: "There were two key points and number one was to run him at Indy, and he did a great job there.
"Number two, we wanted to see what he did with the ALMS programme and he did very well. Ryan is young and I think he has a long career with us."
Briscoe finished fifth at Indianapolis this year racing for a team run by Roger Penske's youngest son Jay. He will partner Helio Castroneves at the team next year.