Townsend Bell has completed a deal to contest the Indianapolis 500 with KV Racing, in a third car alongside Mario Moraes and Paul Tracy.
The 34-year-old American finished 10th at Indy last year during a partial campaign with Dreyer & Reinbold Racing, but does not have a full-time IndyCar drive this season.
He said he was delighted to join the squad co-owned by his sometime Patrick Racing Champ Car team-mate Jimmy Vasser.
"Turning back the clock to 2001, Jimmy was my teammate in my first Champ Car event," said Bell. "Now I have the honour of racing for him and that is very special."
Vasser's co-owner Kevin Kalkhoven added: "Townsend is a proven talent who will provide valuable experience and knowledge to the team during the month of May."
Bell's deal only covers the second week of Indianapolis practice and qualifying, so he will not take part in this weekend's Pole Day and second qualifying sessions, which set the first 22 places on the 33-car grid.