| 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 | |
| ITF M25 Santa Margherita | 09/28 16:30 | 26 | Giovanni Fonio v Fabrizio Andaloro | 6-2,6-4 | |
| ITF M25 Santa Margherita | 09/27 17:35 | 25 | Giovanni Fonio v Federico Bertuccioli | 6-4,6-1 | |
| Challenger - Sibiu | 09/22 09:00 | 26 | [288] Ivan Gakhov v Giovanni Fonio [372] | 6-4,6-2 | |
| Challenger - Sibiu | 09/20 12:00 | 25 | Dragos Nicolae Madaras v Giovanni Fonio | 1-6,4-6 | |
| Challenger - Sibiu | 09/19 08:55 | 19 | [373] Giovanni Fonio v Eric Vanshelboim [489] | 6-3,6-1 | |
| Challenger - Sibiu | 09/18 10:15 | 14 | Giovanni Fonio v Vlad Andrei Dancu | 6-2,6-3 | |
| Challenger - Sevilla | 09/07 15:00 | 26 | [403] Giovanni Fonio v Bernabe Zapata Miralles [79] | 6-7,4-6 | |
| Challenger - Sevilla | 09/06 10:35 | 25 | [403] Giovanni Fonio v Dalibor Svrcina [222] | 6-3,6-1 | |
| Challenger - Sevilla | 09/05 10:40 | 19 | [285] Oriol Roca Batalla v Giovanni Fonio [403] | 2-6,1-6 | |
| Challenger - Sevilla | 09/04 14:05 | 14 | [403] Giovanni Fonio v Andrey Chepelev [346] | 6-3,6-4 | |
| Challenger - Como | 08/29 08:00 | 19 | [311] Nicolas M D Alboran v Giovanni Fonio [403] | 7-6,4-6,6-3 |
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).