Grouillard joined Ligier to fill in the seat left by Stefan Johansson and was the team-mate to René Arnoux for 1989. He qualified 22nd in his first race in Brazil and finished 9th. At Imola, he overcame spinning his car to start in 10th, but was disqualified when mechanics worked on his car during a red flag stint, caused by the accident of Gerhard Berger at Tamburello. He started outside the top 10 at Monaco and Mexico, finishing 8th in the latter but was unable to qualify in Phoenix and Montréal. He started from 17th at his home race at the French Grand Prix and drove to 6th, despite having issues with the tyres and gearbox, scoring his only World Championship point. For the last six races, Grouillard failed to qualify higher than 20th and did not qualify in Portugal. In qualifying for the Belgian Grand Prix at Spa, Grouillard impeded the Lotus of Nelson Piquet by staying on the racing line whilst the Brazilian was on his last flying lap. On the dirty line, Piquet spun off and shook his fist at Grouillard as he passed by. This cost the triple World Champion his chances in qualifying and the race, and it was to be the first of such incidents involving Grouillard's misuse of his mirrors. At Adelaide, he spun which followed a heavy crash in the rain. In fact, for the season ending Australian Grand Prix in Adelaide, he kept the Ligier mechanics busy by spinning off and hitting the concrete walls twice during practice and qualifying as well as in the race morning warm up session (which was wet) and the race.