Jerome D'Ambrosio will be the Lotus team's third driver during the 2012 season, the outfit announced on Tuesday.
The Belgian, who made his grand prix debut with the Virgin Racing team last year, was left without a racing seat after the squad signed Charles Pic to partner Timo Glock in 2012.
D'Ambrosio will attend all races this year, working with race drivers Kimi Raikkonen and Romain Grosjean.
He will stand in for either of the two race drivers if required.
"It's a great feeling to be joining Lotus F1 Team," said D'Ambrosio. "It's an exciting next step in my career. I contested a complete season in F1 as a race driver for a smaller team where I learnt a lot about Formula 1.
"Now, I have the opportunity to work with one of the top teams with great potential for my future development. With my recent race experience, I know I can make a valuable contribution.
"Of course, I would love to be racing, but racing with a top team. Being associated with Lotus F1 Team should be more beneficial and this is the choice I have made. This opportunity is one I couldn't afford to miss. My desire to get back in a race seat in the future is motivating me to do the best job possible in my new position."
Team boss Eric Boullier added: "To have a third driver who is highly motivated, fresh and talented and who contested the full 2011 season is highly beneficial for us. In Jerome we have someone we know well who integrates beneficially with the squad.
"He impressed as reserve driver for us in 2010 and at the end of that year he made a strong showing in the young driver test. He also showed strongly in his rookie season as an F1 race driver. I am looking forward to working with Jerome again and think he is a perfect addition to our driving strength."