Ex-Formula 1 racer Felipe Nasr will join Carlin for Sunday's St. Petersburg IndyCar race, while Conor Daly has been signed to sub for Max Chilton in four oval races.
Nasr, who impressed the Carlin team in a truncated wet/dry test session at Circuit of The Americas last month, having also driven in the Sebring test last week, will join Max Chilton at St. Petersburg to make his IndyCar debut.
The Brazilian driver raced with Carlin during the formative years of his career, claiming the British Formula 3 championship with the team in 2011 and later fought for the GP2 Series title in 2013 and 2014, with several race wins to his name.
Nasr then joined the Sauber F1 team in 2015, scoring 29 points for the Swiss outfit in a two-year spell, and also won the 2018 IMSA Prototype championship.
"It's nice to see that all the work we've put into this program together has finally paid off," said Nasr.
"I'm thankful for Trevor Carlin for giving me the opportunity to drive the No. 31 Carlin Chevrolet this weekend and to Chevy for supporting this program.
"I'm very keen to contribute to the team with my experience and my knowledge and to hopefully show that the speed we had at Sebring a few days ago will translate onto the streets of St. Petersburg.
"I know the team has been working really hard over the offseason and I'm very excited to get out on track first thing on Friday morning."
Sergio Sette Camara, who shared the #31 car with compatriot Nasr in testing at Austin, was yesterday announced as a Red Bull/AlphaTauri test and reserve driver, and has taken a similar role with the Dragon Formula E team.
Carlin also revealed via social media that Daly will return to the team for the races at Texas, Richmond, Iowa and Gateway.
American driver Daly will, like last year, substitute for Max Chilton on all ovals bar the Indianapolis Motor Speedway.
Daly will hence compete for a full IndyCar season, since he is racing the road/street courses and the Indianapolis 500 for the Chevrolet-powered Ed Carpenter Racing team.