The 2018 Autobacs Super GT Series was the twenty-sixth season of the Japan Automobile Federation Super GT Championship including the All Japan Grand Touring Car Championship (JGTC) era and the fourteenth season the series has competed under the Super GT name. It was the thirty-sixth overall season of a national JAF sportscar championship dating back to the All Japan Sports Prototype Championship. The season began on April 8 and ended on November 11, after 8 races.
In the GT500 class, Team Kunimitsu won their first-ever championship with the all-star lineup of series veteran Naoki Yamamoto and 2009 Formula One champion Jenson Button, narrowly beating defending champions Ryō Hirakawa and Nick Cassidy at the final race in Motegi to clinch the title after both teams came in to the race tied in points. It was the first championship title for Honda in the GT500 class since 2010. Yamamoto, who had won the 2018 Super Formula title before the season finale, became just the fourth driver to win both the GT500 and Super Formula titles in the same year, while Button became the first rookie to win the GT500 title since Tora Takagi in 2005.
In the GT300 class, the No. 65 LEON CVSTOS AMG fielded by K2 R&D LEON Racing won the championship in Motegi after overcoming a 12-point deficit over the then-points leader No. 55 ARTA BMW, giving series veteran Haruki Kurosawa and Naoya Gamou their first championship title in the series. The No. 55 ARTA team, despite winning two races in the season, were ultimately too inconsistent in their championship challenge, as two races without scoring a point coupled with poor performance in both Sugo and Motegi ultimately cost them the championship over the more consistent LEON AMG. The No. 31 Toyota Prius apr GT of Koki Saga and Kohei Hirate would finish third, just one point behind the ARTA BMW, while defending champions Goodsmile Racing finished fourth after a poor start to the season and a tire issue in Autopolis ultimately cost them the chance to defend the title.