| ITF M25 Muttenz | 08/18 07:00 | 25 | Jeffrey Von Der Schulenburg 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] Riccardo Balzerani 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 | |
| Challenger Milan | 06/22 13:20 | 26 | [457] Giovanni Fonio v Alexander Shevchenko [173] | 3-6,6-7 | |
| Challenger Milan | 06/21 08:30 | 25 | [457] Giovanni Fonio v Matteo Martineau [375] | 6-3,7-6 | |
| Challenger Milan | 06/20 10:45 | 19 | [398] Samuel Vincent Ruggeri v Giovanni Fonio [457] | 5-7,0-6 | |
| Challenger Milan | 06/19 12:25 | 14 | Simone Roncalli 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 | |
| Challenger Forli | 05/30 08:00 | 19 | [282] Kimmer Coppejans v Giovanni Fonio [471] | 3-6,6-4,7-6 | |
| Challenger Forli | 05/29 08:00 | 14 | [471] Giovanni Fonio v Maxime Janvier [285] | 6-7,6-4,6-4 | |
| Challenger Vicenza | 05/25 15:00 | 26 | [471] Giovanni Fonio v Andrea Pellegrino [222] | 6-7,3-6 | |
| Challenger Vicenza | 05/24 08:30 | 25 | [471] Giovanni Fonio v Genaro Alberto Olivieri [249] | 6-3,6-4 | |
| Challenger Vicenza | 05/23 08:00 | 19 | [352] Mats Rosenkranz v Giovanni Fonio [471] | 4-6,3-6 | |
| Challenger Vicenza | 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 Roma | 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).