Esteban Guerrieri will contest the rest of the Formula Renault 3.5 season for Ultimate-Signature in place of Brazilian Claudio Cantelli.
The change will commence from Silverstone this weekend, and follows Guerrieri being replaced in Ultimate's sister British Formula 3 team by Alastair Jackson for the last round at Rockingham.
Guerrieri has experience at international level having competed in F3000 with BCN in 2004 and made his World Series debut with Fortec at Magny-Cours last year.
"I don't think I should have any problem adapting to the extra power because when I drove the car previously I felt comfortable straight away," said the 23 year-old.
Ultimate boss Barry Walsh added: "We've decided for both teams it would be good to have a bit of a shake-up and give our drivers some new opportunities. By promoting Esteban to our World Series squad, our aim is to have two cars at the sharp end challenging for victories.
"Unfortunately this means Claudio isn't able to complete the season with us, but I would like to thank him for his services and wish him every success in the future."
Guerrieri will partner Fabio Carbone, who has been a frontrunner in the series but has yet to translate his undoubted speed into results.