| ITF M25 Loule | 03/04 13:50 | 28 | Giovanni Fonio v Lucas Poullain | 4-6,6-7 | |
| ITF M25 Loule | 03/03 14:50 | 27 | Adria Soriano Barrera v Giovanni Fonio | 2-6,4-6 | |
| ITF M25 Loule | 03/02 13:30 | 26 | Guy Den Ouden v Giovanni Fonio | 4-6,4-6 | |
| ITF M25 Loule | 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 Tenerife | 02/10 13:15 | 27 | [159] Ryan Peniston v Giovanni Fonio [364] | 7-5,6-2 | |
| Challenger Tenerife | 02/09 11:00 | 26 | [364] Giovanni Fonio v Bu Yunchaokete [282] | 7-6,6-4 | |
| Challenger Tenerife | 02/07 12:30 | 25 | [351] Christian Harrison v Giovanni Fonio [364] | 5-7,4-6 | |
| Challenger Tenerife Qual | 02/06 13:05 | 19 | [232] Matteo Gigante v Giovanni Fonio [364] | 4-6,4-6 | |
| Challenger Tenerife Qual | 02/06 10:00 | 14 | Alessio De Bernardis v Giovanni Fonio | 0-6,1-6 | |
| Challenger Tenerife | 01/29 10:00 | 14 | [267] Lorenzo Giustino v Giovanni Fonio [366] | 6-3,6-4 | |
| Challenger Nonthaburi | 01/21 03:30 | 28 | [366] Giovanni Fonio v Arthur Cazaux [265] | 5-7,3-6 | |
| Challenger Nonthaburi | 01/20 05:25 | 27 | [366] Giovanni Fonio v Antoine Escoffier [192] | Retired | |
| Challenger Nonthaburi | 01/19 04:55 | 26 | [366] Giovanni Fonio v Benjamin Hassan [298] | 6-7,6-4,6-2 | |
| Challenger Nonthaburi | 01/17 05:15 | 25 | [366] Giovanni Fonio v Denis Yevseyev [305] | 6-2,7-5 | |
| Challenger Nonthaburi | 01/16 06:15 | 19 | [415] Jakub Mensik v Giovanni Fonio [366] | 6-3,6-1 | |
| Challenger Nonthaburi | 01/15 08:25 | 14 | [474] Jisung Nam v Giovanni Fonio [376] | 6-4,4-6,2-6 | |
| Challenger Nonthaburi | 01/10 03:00 | 25 | [376] Giovanni Fonio v Arthur Cazaux [382] | 4-6,4-6 | |
| Challenger Nonthaburi | 01/09 03:00 | 19 | [397] Yuta Shimizu v Giovanni Fonio [393] | 6-4,2-6,5-7 | |
| Challenger Nonthaburi | 01/08 03:00 | 14 | [393] Giovanni Fonio v Akira Santillan [389] | 5-7,6-3,6-3 | |
| Challenger Nonthaburi | 01/04 04:30 | 26 | [393] Giovanni Fonio v Dennis Novak [180] | 2-6,1-6 | |
| Challenger Nonthaburi | 01/03 05:10 | 25 | [393] Giovanni Fonio v Thiago Agustin Tirante [225] | 5-7,7-6,7-6 | |
| Challenger Nonthaburi | 01/02 04:35 | 19 | [375] Stuart Parker v Giovanni Fonio [393] | 1-6,4-6 | |
| Challenger Nonthaburi | 01/01 08:45 | 14 | [430] Omni Kumar v Giovanni Fonio [393] | 5-7,2-6 | |
| Challenger Maspalomas | 11/28 11:10 | 19 | Giovanni Fonio v Imanol L Morillo | 6-7,5-7 | |
| Challenger Maspalomas | 11/27 13:40 | 14 | Giovanni Fonio v Ivan Marrero Curbelo | 6-1,6-2 | |
| Challenger Valencia | 11/21 09:00 | 19 | [376] Giovanni Fonio v Gian Marco Moroni [370] | 6-3,3-6,6-7 | |
| Challenger Valencia | 11/20 09:00 | 14 | [295] Oriol Roca Batalla v Giovanni Fonio [369] | 1-6,2-6 | |
| ITF M25 Santa Margherita | 09/29 16:30 | 27 | Giovanni Fonio v Giorgio Tabacco | Retired |
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).