| Challenger de Sanremo | 03/26 08:00 | 14 | [442] Elliot Benchetrit v Giovanni Fonio [328] | 2-6,6-3,4-6 | |
| Challenger de Zadar | 03/21 09:00 | 25 | [328] Giovanni Fonio v Arthur Cazaux [218] | 6-4,4-6,2-6 | |
| Challenger de Zadar | 03/20 09:00 | 168 | [328] Giovanni Fonio v Damien Wenger [403] | 7-5,6-2 | |
| Challenger de Zadar | 03/19 10:30 | 45 | Giovanni Fonio v Patrik Jurina | 6-2,6-2 | |
| Challenger de Székesfehérvár | 03/12 09:00 | 14 | [341] Giovanni Fonio v Elliot Benchetrit [444] | Cancelled | |
| ITF M25 Loulé | 03/04 13:50 | 28 | Giovanni Fonio v Lucas Poullain | 4-6,6-7 | |
| ITF M25 Loulé | 03/03 14:50 | 27 | Adria Soriano Barrera v Giovanni Fonio | 2-6,4-6 | |
| ITF M25 Loulé | 03/02 13:30 | 26 | Guy Den Ouden v Giovanni Fonio | 4-6,4-6 | |
| ITF M25 Loulé | 03/01 15:45 | 25 | Tiago Pereira v Giovanni Fonio | 4-6,6-7 | |
| ITF M25 Faro | 02/23 12:40 | 26 | [486] August Holmgren v Giovanni Fonio [332] | 6-2,3-6,7-5 | |
| ITF M25 Faro | 02/21 11:55 | 25 | [473] Goncalo Oliveira v Giovanni Fonio [332] | 6-7,4-6 | |
| Challenger de Tenerife | 02/10 13:15 | 27 | [159] Ryan Peniston v Giovanni Fonio [364] | 7-5,6-2 | |
| Challenger de Tenerife | 02/09 11:00 | 26 | [364] Giovanni Fonio v Bu Yunchaokete [282] | 7-6,6-4 | |
| Challenger de Tenerife | 02/07 12:30 | 25 | [351] Christian Harrison v Giovanni Fonio [364] | 5-7,4-6 | |
| Challenger Tenerife - Clasificación | 02/06 13:05 | 19 | [232] Matteo Gigante v Giovanni Fonio [364] | 4-6,4-6 | |
| Challenger Tenerife - Clasificación | 02/06 10:00 | 14 | Alessio De Bernardis v Giovanni Fonio | 0-6,1-6 | |
| Challenger de Tenerife | 01/29 10:00 | 14 | [267] Lorenzo Giustino v Giovanni Fonio [366] | 6-3,6-4 | |
| Challenger de Nonthaburi | 01/21 03:30 | 28 | [366] Giovanni Fonio v Arthur Cazaux [265] | 5-7,3-6 | |
| Challenger de Nonthaburi | 01/20 05:25 | 27 | [366] Giovanni Fonio v Antoine Escoffier [192] | Retired | |
| Challenger de Nonthaburi | 01/19 04:55 | 26 | [366] Giovanni Fonio v Benjamin Hassan [298] | 6-7,6-4,6-2 | |
| Challenger de Nonthaburi | 01/17 05:15 | 25 | [366] Giovanni Fonio v Denis Yevseyev [305] | 6-2,7-5 | |
| Challenger de Nonthaburi | 01/16 06:15 | 19 | [415] Jakub Mensik v Giovanni Fonio [366] | 6-3,6-1 | |
| Challenger de Nonthaburi | 01/15 08:25 | 14 | [474] Jisung Nam v Giovanni Fonio [376] | 6-4,4-6,2-6 | |
| Challenger de Nonthaburi | 01/10 03:00 | 25 | [376] Giovanni Fonio v Arthur Cazaux [382] | 4-6,4-6 | |
| Challenger de Nonthaburi | 01/09 03:00 | 19 | [397] Yuta Shimizu v Giovanni Fonio [393] | 6-4,2-6,5-7 | |
| Challenger de Nonthaburi | 01/08 03:00 | 14 | [393] Giovanni Fonio v Akira Santillan [389] | 5-7,6-3,6-3 | |
| Challenger de Nonthaburi | 01/04 04:30 | 26 | [393] Giovanni Fonio v Dennis Novak [180] | 2-6,1-6 | |
| Challenger de Nonthaburi | 01/03 05:10 | 25 | [393] Giovanni Fonio v Thiago Agustin Tirante [225] | 5-7,7-6,7-6 | |
| Challenger de Nonthaburi | 01/02 04:35 | 19 | [375] Stuart Parker v Giovanni Fonio [393] | 1-6,4-6 | |
| Challenger de Nonthaburi | 01/01 08:45 | 14 | [430] Omni Kumar v Giovanni Fonio [393] | 5-7,2-6 |
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).