Formula 3 front-runners Tom Blomqvist and Will Buller will make their GP3 test debuts with Carlin at Valencia this week alongside team regular Conor Daly.
American driver Daly, who finished 17th in GP3 with Carlin this year, will drive on both days of the test, while British duo Blomqvist and Buller will take part on one day each.
"It's great to have three such experienced drivers in the car this week," said team boss Trevor Carlin.
"Obviously we welcome Conor back with open arms; he was extremely impressive this season on tracks he had never raced on before. To have him back in the car for testing and aiding our development programme further will be extremely helpful.
"Both Will and Tom are very talented drivers and it will be interesting to see how they adapt to the challenges of the GP3 car."
Both Blomqvist and Buller had race-winning campaigns in F3 this year; the former taking one win on his way to sixth in the German series while Buller won once en route to fourth in the British championship and also finished sixth at Macau last weekend.
Blomqvist will switch to Carlin after spening day one with Status Grand Prix alongside British F3 National Class champion Kotaro Sakurai and Facu Regalia.
Among the other drivers confirmed for day one of the test are Daniel Abt, Victor Guerin and Marlon Stockinger at champion squad ART, and Japanese F3 champion Yuhi Sekiguchi, who will test for RSC Mucke alongside ADAC Formel Master title winner Pascal Wehrlein.
Britain's Will Stevens, a front-runner in the Formula Renault Eurocup this year, will turn out for MW Arden alongside Fabio Gamberini and Maxim Zimin, while Atech CRS will run GP3 race-winner Tamas Pal Kiss alongside 2012 race driver Ethan Ringel.
Tech 1 will field little-known pair Picho Toledano and Lorenzo Camplese while the Manor line-up will be its regular race driver Matias Laine, Dmitry Suranovich and Formula Renault UK runner-up Tio Ellinas.
Completing the field is Jenzer Motorsport, which will have Robert Visoiu, Patric Niederhauser and Michael Heche behind the wheel of its machines, and Trident, which will again partner with Addax to run Yuji Grigorenko and Michele Cerruti.