Raikkonen spent the 2010 season in a Citroen Junior Team C4 WRC before switching to Citroen’s DS3 WRC for 2011. Co-driven by fellow Finn Kaj Lindstrom, Raikkonen finished 10th in the drivers’ championship standings on both occasions.
The highlights of his WRC stint included a stage win on ADAC Rallye Deutschland in 2010 and a fifth place finish on the Rally of Turkey earlier that year.
Despite not ruling out a further season in the WRC, the 32-year-old had been the subject of considerable speculation linking him with a return to Formula One for several months.
He said: “I’m delighted to be coming back to Formula One after a two-year break, and I’m grateful to Lotus Renault GP for offering me this opportunity. My time in the World Rally Championship has been a useful stage in my career as a driver, but I can't deny the fact that my hunger for F1 has recently become overwhelming.
“It was an easy choice to return with Lotus Renault GP as I have been impressed by the scope of the team's ambition. Now I’m looking forward to playing an important role in pushing the team to the very front of the grid.”