| 1 | Okayama GT 300 km Race | 
Regulation changesThe GTA confirmed several regulation changes for the 2025 Super GT season.
- The series reverted to the two-part knockout qualifying format used from 2013 to 2023. The only change from 2023 was the number of cars that would participate in Q2. In GT500, the top 10 cars in Q1 would advance to Q2, instead of the top eight. In GT300, where the field is split into two groups for Q1, the top nine cars in each group advance to Q2, meaning that 18 cars would participate in Q2.
- * The Fuji GT Sprint Race qualifying format consisted of a single 20-minute GT300 session and a 10-minute GT500 session, held each morning before the races on Saturday and Sunday.
- The GT300 championship points system was changed, awarding 25 points to the first place team and drivers, 20 for second, 16 for third, then 13, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, and 1 for the top 15 cars. In addition, only the seven highest-scoring rounds counted towards the drivers' and teams' championships at the end of the season. This was to accommodate only 18 full-time GT300 teams being eligible to enter the Sepang round due to limited garage space.
- * For the Fuji GT Sprint Races, each race would award half points, and the points from both races would be added up at the end of both races. The points would be awarded to both entered drivers regardless of their individual results in each race.
- In both classes, qualifying points reverted to awarding only one point to the pole-winning team and drivers.
- The GT300 success weight formula was changed, including the modification of refueling times as a form of success ballast. The nominal success weight limit was raised back to 100 kilograms, but the maximum amount of physical ballast that could be loaded remained at 50 kg. Cars that attained more than 50 kg of nominal success weight would have to install a GTA-supplied refueling restrictor, the diameter of which would be announced in a pre-race bulletin.
- From the second round onward, GT500 tire manufacturers that have not won a race during the season may bring in one extra set of dry tires per weekend. All teams must bring at least one set of heavy rain tires.
- During the reconnaissance lap, all cars must maintain a minimum speed of 80 kilometers per hour. From the formation lap until the start of the race, all cars must be within five car lengths of the car in front.
- Race control can now impose time penalties during a race for various infractions.
Teams and driversGT500Entrant & driver changesHonda announced its driver line-ups on 11 December 2024. Toyota announced its driver line-ups on 25 December 2024. Nissan announced its line-ups on 17 January 2025.
- Four-time GT500 champion Ronnie Quintarelli retired from the Super GT Series after the 2024 season, becoming a NISMO ambassador and an advisor to the GT500 program.
- Mitsunori Takaboshi was promoted to the flagship NISMO team from NISMO NDDP to replace Quintarelli, reuniting him with Katsumasa Chiyo
- Daiki Sasaki returned to GT500 after spending a year in GT300 with Kondo Racing, replacing Takaboshi at NISMO NDDP.
- Tokyo Radiator will take over primary sponsorship of Team Impul from Marelli, which though its predecessor Calsonic, had been the team's primary sponsor since 1982.
Mid-season changesGT300Vehicle changesEntrant changes- During the first official pre-season test at Okayama, JLOC elected to use the GT300 champion's number "0" plate for the championship-winning No. 88 car that was driven by Takashi Kogure and Yuya Motojima.
- After parting ways with Arnage Racing, Anest Iwata established its own team, Anest Iwata Racing. The team will receive vehicle maintenance support from GAINER. 2008 GT300 champion and former Nissan factory driver Hironobu Yasuda returned to the series after a year away, replacing Yuga Furutani, who left the team to focus on his Super Formula Lights campaign with TOM'S.
- apr announced a new lineup for the No. 31 Lexus LC500h GT, with former Jota Sport WEC driver Oliver Rasmussen making his series debut, and Miki Koyama making her full-time GT300 debut after running part-time with Arnage Racing and R'Qs Motor Sports. They replaced Kazuto Kotaka, who became Toyota's full-time GT500 reserve driver, and Jin Nakamura, who moved to the Formula Regional European Championship.
- In the No. 30 apr Toyota GR86, two-time GT300 champion Manabu Orido returned to full-time driving, replacing Rikuto Kobayashi, while Ryo Ogawa returned as the team's third driver for the long-distance events. The No. 30 Toyota GR86 also changed from Yokohama to Michelin tires.
- 2024 FIA F4 Japanese Champion and Honda Formula Dream Project driver Yuto Nomura joined Team UpGarage for his Super GT debut, replacing Syun Koide after his promotion to GT500.
- With new title sponsorship from car wash equipment manufacturer Hyper Water, INGING Motorsport announced former Toyota Gazoo Racing Driver Challenge F4 driver Kazuhisa Urabe as its third driver, replacing veteran Hiroki Katoh, who focused exclusively on his role as team director.
- TGR-DC driver Yuki Sano joined SHADE Racing as its third driver for the long-distance races. Due to SHADE Racing's withdrawal from Autopolis, Sano would only enter the Golden Week race at Fuji.
- Togo Suganami rejoined K2 R&D LEON Racing for the first time since 2021. To replace Suganami at Hoppy Team Tsuchiya, Kimiya Sato was returned as a full-time driver after spending last season as the team's third driver.
- Porsche returned to GT300 for the first time since 2021 via the new team, run by Kiyoto Fujinami's KF Motorsport team and backed by luxury hotel company FAV Hotel. The team entered the latest Porsche 911 GT3 R with Yokohama tires. Two-time GT300 champion and team owner Fujinami was announced as one of the team's drivers, joined by four-time Porsche Carrera Cup Japan champion Tsubasa Kondo, who returned to the series for the first time since 2022. 2024 Porsche Supercup runner-up Harry King would join the team as its third driver for the Golden Week race at Fuji.
- Kazuki Oki, who was GAINER's third driver for the final race of the 2025 season, replaced Keishi Ishikawa as a full-time driver of the No. 11 Nissan Fairlady Z GT300.
- Two-time GT500 champion Kohei Hirate left HELM Motorsports and returned to Kondo Racing to drive the No. 56 Nissan GT-R NISMO GT3. GT World Challenge Asia race winner Yu Kanamaru joined Kondo Racing as its third driver.
- HELM Motorsports co-owner Reiji Hiraki returned to full-time driving after serving as the team's third driver behind Hirate, and his brother Yuya Hiraki.
- Tomei Sports promoted former TGR-DC driver Rin Arakawa to a full-time role, replacing Takuya Otaki. The team also signed F4 Japan race winner Hironobu Shimizu as its third driver.
- Ponos Racing changed from Michelin to Dunlop tires and, after receiving technical support and vehicle maintenance from GAINER at the start of 2024, moved into its own facility. Ferrari factory GT driver Lilou Wadoux was set to return to the team for the full season, but before the first round, Wadoux departed the team due to scheduling conflicts with the European Le Mans Series and IMSA SportsCar Championship. 2024 GT300 runner-up Takuro Shinohara, who was set to be Ponos Racing's third driver after his departure from K2 R&D LEON Racing, replaced Wadoux for the full season.
- Reigning Porsche Carrera Cup Japan champion Reimei Ito, who joined LM corsa as the third driver at Suzuka, was announced as the team's third driver for the long-distance races.
- R'Qs Motor Sports signed Super Taikyu ST-3 driver Yuma Shoji as the fourth driver, replacing Miki Koyama.
- Team LeMans changed its entrant name to Velorex.
- BMW M Team Studie left the series to compete in GT World Challenge Asia. Seiji Ara followed Studie to race in GT World Asia alongside Tomohide Yamaguchi. Niklas Krütten moved to International GT Open with Team Motopark, while Bruno Spengler left BMW M Motorsport after 13 years to join Bugatti as their official driver.
- CarGuy Racing returned to the series after a two-year hiatus, partnering with, a new organization created by former MOLA and Yogibo Racing team director Misato Haga. Competing as CarGuy MKS Racing, the team entered the No. 7 Ferrari 296 GT3 with Yokohama tires. Former Williams Driver Academy driver and Formula 2 race winner Zak O'Sullivan made his debut in the series, driving alongside 2024 Super Formula Lights runner-up Rikuto Kobayashi, who was originally slated to be Saitama Green Brave's third driver. 2015–16 Asian Le Mans GT champion Keita Sawa was appointed as the third driver.
- Team Mach signed former Honda factory driver and 2023 Super Formula Lights champion Iori Kimura, who returned to the series after a year in Super Formula with B-Max Racing Team.
- NILZZ Racing signed SRO Japan Cup and Super Taikyu class winner Daiki Fujiwara as its third driver.
- Earl Bamber Motorsport announced its Super GT debut as the wildcard entry for the Sepang round, competing as EBM Giga Racing. EBM fielded two entries from two different manufacturers, with two different tire suppliers: The No. 333 Aston Martin Vantage AMR GT3 Evo, driven by Jazeman Jaafar and Kerong Li, and the No. 611 Porsche 911 GT3 R, driven by Porsche Motorsport Asia Pacific driver Dorian Boccolacci and Adrian D'Silva.
GT300 mid-season changesResultsDrivers credited with winning Pole Position and the race's fastest lap for their respective teams are indicated in bold text.
| Round | Circuit | Class | Pole position | Fastest lap | Race winner | Report | | 1 | 
Championship standingsDrivers' championships; Race points ;Scoring system
- For the Fuji GT Sprint Races, each race would award half points, and the points from both races would be added up at the end of both races. The points would be awarded to both entered drivers regardless of their individual results in each race.
Teams' championships; Race points ;Scoring system
- For the Fuji Sprint Race, half points to be awarded.
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