Alexander Rossi will return to GP2 with Racing Engineering for the 2015 season, completing the team's line-up alongside Jordan King.
The American, a race winner with Caterham in 2013, completed a part-season with the team last year, before switching to Campos for a one-off appearance at Hockenheim and then sitting out the rest of the campaign while he pursued opportunities in Formula 1.
Rossi, who made his GP2 debut in the Asia series in 2009, said a deal with Racing Engineering had been a long time coming.
"After several years of discussions, at last we have found a way to work together," said the 23-year-old.
"After my 2014 season as the reserve driver at the Caterham and Marussia F1 teams, it is public knowledge that I have been carefully looking over several options for 2015.
"My ultimate goal still remains F1, and GP2 with Racing Engineering is perfect for these objectives.
Team boss Alfonso de Orleans-Borbon added: "I am delighted to have Alex joining us as he has the talent and teamwork necessary for leading the championship this season.
"We have known Alex for many years and our paths have often crossed but not come together.
"With Jordan King, we have a formidable line-up for 2015."
Lazarus has also announced its first signing for this year, retaining Nathanael Berthon for his fourth season in the category.
2015 GP2 FIELD SO FAR
Pierre Gasly, Alex Lynn
Marco Sorensen, Julian Leal
Stoffel Vandoorne, Nobuharu Matsushita
Jordan King, Alexander Rossi
Mitch Evans, Artem Markelov
Raffaele Marciello, Rene Binder
Arthur Pic, Rio Haryanto
Sergey Sirotkin, tba
Norman Nato, Andre Negrao
Nathanael Berthon, tba
Yet to announce drivers: MP, Status, Hilmer