Teams and drivers
Every Honda-powered car used a Honda HR-414E engine and every Toyota-powered car used a Toyota RI4A engine.
| Team | Engine | No. | Driver | Rounds |
|---|---|---|---|---|
 TCS Nakajima Racing | Honda | 1 | Naoki Yamamoto [1] | All |
| 64 | Toshiki Oyu [2] | All | ||
| Kondo Racing | Toyota | 3 | Kenta Yamashita [3] | All |
| 4 | Yuichi Nakayama [4] | 1–5 | ||
 Sacha Fenestraz [3] | 6–7 | |||
| Docomo Team Dandelion Racing | Honda | 5 | Nirei Fukuzumi [2] | All |
| 6 | Ukyo Sasahara [4] | 1–2 | ||
| Tadasuke Makino [1] | 3–7 | |||
 carrozzeria Team KCMG | Toyota | 7 | Kazuto Kotaka [4] | 1–5, 7 |
| Kamui Kobayashi [3] | 6 | |||
| 18 | Yuji Kunimoto [3] | All | ||
| Drago Corse with ThreeBond [5] | Honda | 12 |  Tatiana Calderón [1] | 1–2, 6–7 |
| Koudai Tsukakoshi [6] | 3–5 | |||
| NTT Communications ROOKIE | Toyota | 14 | Kazuya Oshima [3] | All |
| Red Bull Mugen Team Goh | Honda | 15 | Hiroki Otsu [7] | All |
| Team Mugen [2] | Honda | 16 | Tomoki Nojiri [2] | All |
| carenex Team Impul | Toyota | 19 | Yuhi Sekiguchi [3] | All |
| 20 | Ryō Hirakawa [3] | 1–3, 5–7 | ||
| Mitsunori Takaboshi [8] | 4 | |||
| Kuo Vantelin Team TOM'S | Toyota | 36 | Kazuki Nakajima [3] | 1, 6 |
| Giuliano Alesi [9] | 2–5, 7 | |||
| 37 | Ritomo Miyata [3] | All | ||
| P.mu/Cerumo・INGING | Toyota | 38 | Sho Tsuboi [3] | All |
| 39 | Sena Sakaguchi [3] | All | ||
| B-Max Racing [2] | Honda | 51 | Nobuharu Matsushita [10] | 2–7 |
- Yves Baltas was scheduled to compete for B-Max Racing, but did not enter any rounds. [11]
Team changes
- Team Mugen run one car, as the other car will be run together with Servus under Team Goh. The team named Red Bull Mugen Team Goh.
- Rookie Racing who previously operated by Cerumo, would run independently by themselves. The team get new title partner from NTT Communications, the team named NTT Communications ROOKIE.
- Team Impul runs new sponsorship from Itochu as they will run under black gold colour. The team rebranded as carenex Team Impul.
Driver changes
- Three-time and defending series champion Naoki Yamamoto moved to TCS Nakajima Racing after spending two seasons with Dandelion Racing. This was Yamamoto's first time driving for Nakajima Racing since his rookie season in 2010. [2]
- Tadasuke Makino moved to Docomo Team Dandelion Racing after two seasons with Nakajima Racing. [2]
- Hiroki Otsu gets a full time seat after an appearance in the last round in 2020, as he raced with Red Bull Mugen Team Goh. [7]
- Reigning Super Formula Lights champion Ritomo Miyata drove full-time for Vantelin Team TOM's, after running two races in 2020 in relief of Kazuki Nakajima. [3]
- Reigning Formula Regional Japanese Champion Sena Sakaguchi drove full-time for P.mu/Cerumo・INGING, after appearing in the 2020 Okayama round in relief of Kenta Yamashita. [3]
- Two-time series champion Hiroaki Ishiura has retired from the series.
- 2019 series champion Nick Cassidy has exited the series, following his move to the FIA Formula E World Championship with Envision Virgin Racing.
In-season changes
Illness:
- Tadasuke Makino: missed the first two rounds of the season due to a bout with meningitis. Ukyo Sasahara was his replacement.
Visa issues:
- Sacha Fenestraz: missed the first five rounds because of visa issues. Yuichi Nakayama was his replacement.
International protocols:
Drivers who participated in 2021 FIA World Endurance Championship races or testing sessions missed rounds because of Japanese 14-day quarantine rules. Date clashes were with the 6 Hours of Spa-Francorchamps on 1 May, which clashed with Suzuka (25 April) and Autopolis (16 May), the 8 Hours of Portimão, which clashed with Sugo (19 June), and the 8 Hours of Bahrain, which clashes with the Suzuka date on 31 October.
- Kamui Kobayashi: missed all but the sixth round at Motegi due to commitments in the WEC and IMSA. Kazuto Kotaka was his replacement.
- Kazuki Nakajima: missed both Suzuka rounds, Autopolis, Sugo, and the fifth round at Motegi. Giuliano Alesi was his replacement, and won a rain shortened race from pole position at Autopolis.
- Tatiana Calderon: missed Autopolis, Sugo, and the fifth round at Motegi (was able to participate in the April Suzuka round because of local regulations with her licence, which is from the ACC, the Colombian ASN of the FIA, unlike the Japanese drivers, who have JAF licences). Koudai Tsukakoshi was her replacement.
- Ryo Hirakawa: missed Sugo. Mitsunori Takaboshi was his replacement.
Other
- Nobuharu Matsushita: joined B-Max Racing from the second round at Suzuka. He was initially denied an engine lease from Honda, after signing a factory racing contract with Nissan in the Super GT Series. This prevented him from racing in the opening round at Fuji. Honda would reverse their decision after Masaya Nagai replaced Hiroshi Shimizu as the Director of Motorsport at Honda. [12]
