Devlin DeFrancesco will contest the rest of the 2018 GP3 season with MP Motorsport, it has been announced.
Long-time GP2/Formula 2 squad MP entered GP3 for the first time this year, replacing DAMS.
Dorian Boccolacci and Niko Kari are the team's two full-time drivers, while the third car was shared by one-offs Will Palmer and Renault junior Christian Lundgaard in the first two rounds of the season.
DeFrancesco will take over from this weekend's Austria onwards, adding to his European F3 duties.
"I was originally asked to race GP3 last year by a few teams and asked if I would consider a few 1 off races this year" DeFrancesco said.
"After considering changes the F3 and GP3 series are taking for 2019, switching to GP3 seems like the best option for the future.
"It will definitely be tough never having tested the car before but I’m super excited and up for the challenge."
The 18-year-old started the season in F3 with Carlin but, after failing to score points in the first two rounds, DeFrancesco withdrew from last weekend's Norisring round to have dental surgery.
However, he will continue to have a part-time presence in F3.
"I’m fortunate I’m part of Carlin also and on some of the free weekends I’ll race FIA [F3] for additional track time," he added.
"My first impressions of MP are very positive, they seem like a great bunch of guys and definitely work hard, nobody’s more excited to start than I am."
DeFrancesco has been racing in junior single-seaters since 2016, racing in F4 level and taking fifth in the British championship that year.
He moved up to Euroformula Open in 2017, finishing third there.
MP team manager Sander Dorsman added: "We are happy to welcome Devlin in our team. His progress in British F4 and Euroformula Open was exciting to watch, and I’m sure that with us he will deliver on that promise.
"As a team, we will be there to help him get on with his first GP3 race weekend, and I’m convinced he will transform the experience into an ever-improving GP3 debut season."
Paul Ricard GP3: Ilott resists Piquet for maiden win
Red Bull Ring GP3: Ferrari's Ilott takes maiden pole