In a statement, the team said they had renewed their "technical and racing agreement" with the Finn, extending his stay into a fifth consecutive year.
The 37-year-old was also with Ferrari for three years from 2007-09.
He is fifth in the championship standings, with team-mate Sebastian Vettel leading Mercedes driver Lewis Hamilton by 14 points.
Raikkonen won Ferrari's last drivers' title in 2007.
Vettel, 30, is out of contract at Ferrari at the end of the year.
BBC Sport's chief F1 writer Andrew Benson
Kimi Raikkonen staying at Ferrari is no surprise at all, despite president Sergio Marchionne calling the Finn "a laggard" earlier this season.
The decision almost certainly means number one driver Sebastian Vettel is also staying. This has not been announced yet but Raikkonen has been a good back-up to the German this season - surrendering two victory chances relatively uncomplainingly in Monaco and Hungary to aid his team-mate's title chances.
The two men get on well and a team would no longer sign Raikkonen as a number one driver - from time to time there are glimpses of the electrifying form that won him so many fans in the mid-2000s, but usually he is a beat or two behind the absolute pace these days.
But he does a job for Ferrari and, with no obvious better option for that support role, retaining him makes sense for a team with an inherently conservative approach to the driver market.
Ferrari have extended former world champion Kimi Raikkonen's contract until the end of the 2018 season.