| Club: | Fluminense |
| Season: | 2023[1] |
| Chairman: | Mário Bittencourt[2] |
| Manager: |  Fernando Diniz |
| Stadium: | Maracanã |
| League: | Série A |
| League Result: | 7th |
| Cup1: | Campeonato Carioca |
| Cup1 Result: | Champions[3] |
| Cup2: | Copa do Brasil |
| Cup2 Result: | Round of 16 |
| Cup3: | Copa Libertadores |
| Cup3 Result: | Champions[4] |
| Cup4: | FIFA Club World Cup |
| Cup4 Result: | Runners-up |
| League Topscorer: | Germán Cano (10) |
| Season Topscorer: | Germán Cano (40) |
| Pattern La1: | _fluminense22h |
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| Prevseason: | 2022 |
| Nextseason: | 2024 |
The 2023 season was Fluminense's 122nd season in the club's history.[5] Fluminense competed in the Campeonato Carioca, Copa do Brasil, Série A, Copa Libertadores and FIFA Club World Cup.[6]
| Games played | 72 (15 Carioca, 4 Copa do Brasil, 13 Copa Libertadores, 38 Série A, 2 Club World Cup) |
| Games won | 37 (10 Carioca, 2 Copa do Brasil, 8 Copa Libertadores, 16 Série A, 1 Club World Cup) |
| Games drawn | 13 (1 Carioca, 1 Copa do Brasil, 3 Copa Libertadores, 8 Série A, 0 Club World Cup) |
| Games lost | 22 (4 Carioca, 1 Copa do Brasil, 2 Copa Libertadores, 14 Série A, 1 Club World Cup) |
| Goals scored | 115 |
| Goals conceded | 74 |
| Goal difference | +41 |
| Best result | 7–0 (H) v Volta Redonda – Carioca – 2023.03.18 |
| Worst result | 0–4 (A) v Manchester City – Club World Cup – 2023.12.22 |
| Top scorer | Germán Cano (40) |