| ITF M25 Muttenz | 08/18 07:00 | 25 | von Der Schulenburg, Jeffrey v Giovanni Fonio | 5-7,6-7 | |
| Challenger San Benedetto | 07/29 17:55 | 27 | [435] Giovanni Fonio v Luciano Darderi [186] | 4-6,1-6 | |
| Challenger San Benedetto | 07/28 19:30 | 26 | [435] Giovanni Fonio v Frederico Ferreira Silva [249] | 6-4,6-1 | |
| Challenger San Benedetto | 07/26 19:55 | 25 | [231] Alessandro Giannessi v Giovanni Fonio [435] | 3-6,4-6 | |
| Challenger San Benedetto | 07/25 11:00 | 19 | [471] Luca Potenza v Giovanni Fonio [435] | 2-6,3-6 | |
| Challenger San Benedetto | 07/24 13:10 | 14 | [488] Balzerani, Riccardo v Giovanni Fonio [436] | 6-2,3-6,4-6 | |
| Challenger Trieste | 07/18 09:00 | 19 | [345] Lukas Neumayer v Giovanni Fonio [436] | 3-6,7-6,6-2 | |
| Challenger Trieste | 07/17 08:00 | 14 | Alessandro Pecci v Giovanni Fonio | 7-6,2-6,6-7 | |
| Challenger Verona | 07/10 13:30 | 14 | [333] Pedro B Dias v Giovanni Fonio [441] | 7-5,1-6,7-5 | |
| Challenger Todi | 07/06 13:00 | 26 | [232] Luciano Darderi v Giovanni Fonio [441] | 6-3,7-6 | |
| Challenger Todi | 07/05 11:05 | 25 | [441] Giovanni Fonio v Dmitry Popko [195] | 6-4,3-6,6-1 | |
| Challenger Todi | 07/04 10:20 | 19 | [333] Pedro B Dias v Giovanni Fonio [441] | 3-6,2-6 | |
| Challenger Todi | 07/03 11:25 | 14 | Mohamed Safwat v Giovanni Fonio | 0-6,1-6 | |
| Challenger Troyes | 06/27 15:00 | 19 | [367] Clement Tabur v Giovanni Fonio [441] | 6-7,7-5,7-6 | |
| Challenger Troyes | 06/26 14:05 | 14 | Boris Fassbender v Giovanni Fonio | 0-6,2-6 | |
| Milan, Italy | 06/22 13:20 | 26 | [457] Giovanni Fonio v Alexander Shevchenko [173] | 3-6,6-7 | |
| Milan, Italy | 06/21 08:30 | 25 | [457] Giovanni Fonio v Matteo Martineau [375] | 6-3,7-6 | |
| Milan, Italy | 06/20 10:45 | 19 | [398] Samuel Vincent Ruggeri v Giovanni Fonio [457] | 5-7,0-6 | |
| Milan, Italy | 06/19 12:25 | 14 | Roncalli, Simone v Giovanni Fonio | 6-4,2-6,5-7 | |
| Challenger Perugia | 06/06 08:00 | 19 | [450] Giovanni Fonio v Elliot Benchetrit [447] | 6-7,6-7 | |
| Challenger Perugia | 06/05 08:00 | 14 | [282] Michael Geerts v Giovanni Fonio [470] | 3-6,6-3,5-7 | |
| Forli 6, Italy | 05/30 08:00 | 19 | [282] Kimmer Coppejans v Giovanni Fonio [471] | 3-6,6-4,7-6 | |
| Forli 6, Italy | 05/29 08:00 | 14 | [471] Giovanni Fonio v Maxime Janvier [285] | 6-7,6-4,6-4 | |
| Challenger - Vicence | 05/25 15:00 | 26 | [471] Giovanni Fonio v Andrea Pellegrino [222] | 6-7,3-6 | |
| Challenger - Vicence | 05/24 08:30 | 25 | [471] Giovanni Fonio v Genaro Alberto Olivieri [249] | 6-3,6-4 | |
| Challenger - Vicence | 05/23 08:00 | 19 | [352] Mats Rosenkranz v Giovanni Fonio [471] | 4-6,3-6 | |
| Challenger - Vicence | 05/22 08:00 | 14 | Giorgio Tabacco v Giovanni Fonio | 0-6,0-6 | |
| Challenger - Francavilla | 05/16 17:00 | 25 | [307] Hernan Casanova v Giovanni Fonio [457] | 7-6,6-1 | |
| ATP - Rome | 05/07 13:30 | 14 | [460] Giovanni Fonio v Emil Ruusuvuori [59] | 4-6,7-6,3-6 | |
| ITF - M25 Santa Margherita | 04/20 12:00 | 26 | Giovanni Fonio v Gabriele Piraino | 2-6,5-7 |
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).