Haas retained Grosjean for the 2018 season where he again partnered Magnussen. At the Azerbaijan Grand Prix, Grosjean crashed behind the safety car whilst running in 6th place. His engineer incorrectly blamed the cause of the crash on Sauber driver Marcus Ericsson, saying, "I think Ericsson hit us." At the Spanish Grand Prix, Grosjean was the cause of a crash on the opening lap. Whilst making his way through turn 3, he lost control of his Haas after running through dirty air. This caused him to spin across the track into the path of the cars behind him, causing a large amount of smoke in the process. He was then hit by Hülkenberg and Gasly, eliminating all three from the race. In the Austrian Grand Prix, Grosjean finished 4th, his best result in his career at Haas and his first points finish in 2018. Grosjean was disqualified from the Italian Grand Prix after the floor of his car was found to be illegal, taking away a 6th-place finish; although the team appealed this, the decision was upheld. Grosjean finished the season 14th with 37 points.