| Challenger de Todi | 07/04 10:20 | 19 | [333] Pedro B Dias v Giovanni Fonio [441] | 3-6,2-6 | |
| Challenger de Todi | 07/03 11:25 | 14 | Mohamed Safwat v Giovanni Fonio | 0-6,1-6 | |
| Challenger de Troyes | 06/27 15:00 | 19 | [367] Clement Tabur v Giovanni Fonio [441] | 6-7,7-5,7-6 | |
| Challenger de Troyes | 06/26 14:05 | 14 | Boris Fassbender v Giovanni Fonio | 0-6,2-6 | |
| Challenger de Milán | 06/22 13:20 | 26 | [457] Giovanni Fonio v Alexander Shevchenko [173] | 3-6,6-7 | |
| Challenger de Milán | 06/21 08:30 | 25 | [457] Giovanni Fonio v Matteo Martineau [375] | 6-3,7-6 | |
| Challenger de Milán | 06/20 10:45 | 19 | [398] Samuel Vincent Ruggeri v Giovanni Fonio [457] | 5-7,0-6 | |
| Challenger de Milán | 06/19 12:25 | 14 | Simone Roncalli v Giovanni Fonio | 6-4,2-6,5-7 | |
| Challenger de Perugia | 06/06 08:00 | 19 | [450] Giovanni Fonio v Elliot Benchetrit [447] | 6-7,6-7 | |
| Challenger de Perugia | 06/05 08:00 | 14 | [282] Michael Geerts v Giovanni Fonio [470] | 3-6,6-3,5-7 | |
| Challenger de Forlì | 05/30 08:00 | 19 | [282] Kimmer Coppejans v Giovanni Fonio [471] | 3-6,6-4,7-6 | |
| Challenger de Forlì | 05/29 08:00 | 14 | [471] Giovanni Fonio v Maxime Janvier [285] | 6-7,6-4,6-4 | |
| Challenger de Vicenza | 05/25 15:00 | 26 | [471] Giovanni Fonio v Andrea Pellegrino [222] | 6-7,3-6 | |
| Challenger de Vicenza | 05/24 08:30 | 25 | [471] Giovanni Fonio v Genaro Alberto Olivieri [249] | 6-3,6-4 | |
| Challenger de Vicenza | 05/23 08:00 | 19 | [352] Mats Rosenkranz v Giovanni Fonio [471] | 4-6,3-6 | |
| Challenger de Vicenza | 05/22 08:00 | 14 | Giorgio Tabacco v Giovanni Fonio | 0-6,0-6 | |
| Challenger de Francavilla | 05/16 17:00 | 25 | [307] Hernan Casanova v Giovanni Fonio [457] | 7-6,6-1 | |
| ATP Roma | 05/07 13:30 | 14 | [460] Giovanni Fonio v Emil Ruusuvuori [59] | 4-6,7-6,3-6 | |
| ITF M25 Santa Margarita | 04/20 12:00 | 26 | Giovanni Fonio v Gabriele Piraino | 2-6,5-7 | |
| ITF M25 Santa Margarita | 04/19 14:10 | 25 | Giovanni Fonio v Toby Martin | 6-0,6-2 | |
| ITF M25 Santa Margarita | 04/12 16:15 | 25 | [489] Matteo Gigante v Giovanni Fonio [454] | 4-6,7-5,7-6 | |
| Challenger de Sanremo | 04/04 08:00 | 19 | [455] Giovanni Fonio v Mate Valkusz [402] | 7-5,4-6,4-6 | |
| Challenger de Sanremo | 04/03 09:30 | 14 | [416] Giovanni Fonio v Alexander Weis [468] | 6-4,6-4 | |
| Challenger Lugano | 03/27 12:35 | 14 | [299] Ruben Bemelmans v Giovanni Fonio [416] | 7-5,6-4 | |
| ITF M25 Opatija | 03/22 10:45 | 25 | [489] Francesco Passaro v Giovanni Fonio [414] | 6-0,4-6,6-2 | |
| ITF M25 Rovinj | 03/15 12:35 | 25 | [362] Ergi Kirkin v Giovanni Fonio [414] | 6-4,7-6 | |
| ITF M25 Porec | 03/09 10:45 | 25 | [335] Filip Misolic v Giovanni Fonio [414] | 7-6,6-4 | |
| ITF M25 Antalya | 02/26 09:15 | 27 | [367] Daniel Michalski v Giovanni Fonio [408] | 6-3,4-6,7-5 | |
| ITF M25 Antalya | 02/25 12:30 | 26 | Giovanni Fonio v Andrea Picchione | Retired | |
| ITF M25 Antalya | 02/22 11:00 | 25 | Togan Tokac v Giovanni Fonio | 1-6,1-6 |
Giovanni Fonio (born 7 May 1998) is an Italian tennis player. He took his first steps in tennis at the age of 5, at the Piazzano tennis club in Novara.
Fonio has a career high ATP singles ranking of 274 achieved on 4 Dicember 2023. He also has a career high doubles ranking of 406 achieved on 15 January 2024.
Fonio has won 2 ATP Challenger doubles title: at the 2023 Internazionali di Tennis del Friuli Venezia Giulia with Francesco Forti and at the 2021 Antalya Challenger III with Riccardo Bonadio.
The greatest victory achieved by Giovanni was certainly during the Yokkaichi Challenger in Japan, on 30 November 2023, when he beat the then top 100 player Yosuke Watanuki in 3 sets (3-6 / 6-2 / 7-5).
An important presence in high-level tournaments was certainly in May 2022 at the qualifiers at the Internazionali d’Italia, unfortunately he lost against Emil Ruusuvuori 2-1 (4-6 / 7-6 / 3-6).