| ITF M15 Antalya | 01/22 10:00 | 28 | Giovanni Fonio v Davide Galoppini | 6-1,6-2 | |
| ITF M15 Antalya | 01/21 13:00 | 27 | Paul Woerner v Giovanni Fonio | 1-6,3-6 | |
| ITF M15 Antalya | 01/20 15:00 | 26 | Calin Manda v Giovanni Fonio | 4-6,3-6 | |
| ITF M15 Antalya | 01/19 12:40 | 25 | Aleksandar Tomas v Giovanni Fonio | 2-6,2-6 | |
| Challenger Antalya | 12/11 10:00 | 28 | [409] Oleg Prihodko v Giovanni Fonio [441] | 1-6,6-1,6-3 | |
| Challenger Antalya | 12/10 07:00 | 27 | [441] Giovanni Fonio v Nick Hardt [350] | 7-6,6-2 | |
| Challenger Antalya | 12/09 09:25 | 26 | [264] Ryan Peniston v Giovanni Fonio [441] | 6-1,4-6,4-6 | |
| Challenger Antalya | 12/08 12:30 | 25 | [466] Jakub Paul v Giovanni Fonio [441] | 1-6,0-6 | |
| Challenger Antalya | 11/29 07:30 | 14 | Marsel Ilhan v Giovanni Fonio | 6-4,3-6,6-4 | |
| Challenger Napoli | 10/11 08:00 | 14 | [303] Javier Barranco Cosano v Giovanni Fonio [437] | 7-5,6-3 | |
| ITF M15 Platja D'Aro | 10/09 09:00 | 28 | [437] Giovanni Fonio v Jose Fco. Vidal Azorin [476] | 3-6,4-6 | |
| ITF M15 Platja D'Aro | 10/08 10:00 | 27 | Giovanni Fonio v Maxime Chazal | 6-3,6-2 | |
| ITF M15 Platja D'Aro | 10/07 13:35 | 26 | Giovanni Fonio v Manish Sureshkumar | 6-0,6-1 | |
| ITF M15 Platja D'Aro | 10/06 10:15 | 25 | Giovanni Fonio v Vitali Shvets | 6-4,6-0 | |
| Challenger Lisbon | 09/26 14:00 | 14 | [458] Daniel Michalski v Giovanni Fonio [439] | 6-4,7-5 | |
| Challenger Bucharest | 09/19 07:30 | 14 | [436] Giovanni Fonio v Oleksii Krutykh [380] | 3-6,1-6 | |
| Challenger Trieste | 07/26 12:35 | 19 | [328] Thiago A Tirante v Giovanni Fonio [442] | 6-3,6-3 | |
| Challenger Trieste | 07/25 11:35 | 14 | [438] Giovanni Fonio v Julian Ocleppo [360] | 3-6,6-4,7-5 | |
| ITF M25 Kottingbrunn | 07/23 10:55 | 27 | Giovanni Fonio v Mate Valkusz | 4-6,0-6 | |
| ITF M25 Kottingbrunn | 07/22 08:00 | 26 | Giovanni Fonio v Sandro Kopp | 6-1,7-5 | |
| ITF M25 Kottingbrunn | 07/21 10:15 | 25 | Giovanni Fonio v Peter Makk | 6-3,7-6 | |
| Challenger Todi | 07/15 17:00 | 26 | [315] Alexander Ritschard v Giovanni Fonio [472] | 6-3,6-4 | |
| Challenger Todi | 07/13 11:00 | 25 | [472] Giovanni Fonio v Lorenzo Giustino [227] | 6-4,6-3 | |
| Challenger Todi | 07/12 13:00 | 19 | [472] Giovanni Fonio v Riccardo Balzerani [492] | 6-3,6-3 | |
| Challenger Todi | 07/11 08:00 | 14 | Giovanni Fonio v Alejandro Mendoza | 6-1,6-1 | |
| ITF M25 Casinalbo | 07/07 08:35 | 26 | Gianmarco Ferrari v Giovanni Fonio | 6-4,7-6 | |
| ITF M25 Casinalbo | 07/05 15:00 | 25 | Luca Parenti v Giovanni Fonio | 0-6,0-6 | |
| ITF M15 Bergamo | 06/23 17:20 | 25 | Giovanni Fonio v Luca Nardi | 6-7,4-6 | |
| ITF M15 Genova | 06/19 13:00 | 28 | Giovanni Fonio v Luca Nardi | 3-6,1-6 | |
| ITF M15 Genova | 06/18 17:30 | 27 | Johan Sebastien Tatlot v Giovanni Fonio | 1-6,6-7 |
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).