| Club: | 1. FSV Mainz 05 |
| Season: | 2019–20 |
| Chrtitle: | Chairman |
| Chairman: | Stefan Hofmann |
| Mgrtitle: | Head coach |
| Manager: | Sandro Schwarz (until 10 November) Achim Beierlorzer (from 18 November) |
| Stadium: | Opel Arena |
| League: | Bundesliga |
| League Result: | 13th |
| Cup1: | DFB-Pokal |
| Cup1 Result: | First round |
| League Topscorer: | Robin Quaison (12) |
| Season Topscorer: | Robin Quaison (12) |
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| Prevseason: | 2018–19 |
| Nextseason: | 2020–21 |
The 2019–20 season was 1. FSV Mainz 05's 121st season in existence and the club's 39th consecutive season in the top flight of German football. In addition to the domestic league, 1. FSV Mainz 05 participated in this season's edition of the DFB-Pokal. The season covered a period from 1 July 2019 to 30 June 2020.
See main article: 2019–20 Bundesliga.
The Bundesliga schedule was announced on 28 June 2019.[2]
See main article: 2019–20 DFB-Pokal.
|-! colspan=14 style=background:#dcdcdc; text-align:center| Goalkeepers|-! colspan=14 style=background:#dcdcdc; text-align:center| Defenders|-! colspan=14 style=background:#dcdcdc; text-align:center| Midfielders|-! colspan=14 style=background:#dcdcdc; text-align:center| Forwards|-! colspan=14 style=background:#dcdcdc; text-align:center| Players transferred out during the season