| Challenger - Todi | 08/15 09:55 | 25 | [322] Giovanni Fonio v Orlando Luz [461] | 7-6,6-4 | |
| Challenger - Cordenons | 08/08 08:00 | 25 | [323] Giovanni Fonio v Nicholas D Ionel [208] | 3-6,7-5,5-7 | |
| Challenger - Liberec | 07/31 14:00 | 25 | [316] Giovanni Fonio v Norbert Gombos [217] | 6-7,4-6 | |
| Challenger - Zug | 07/23 09:00 | 14 | Giovanni Fonio v Dylan Dietrich | 3-6,3-6 | |
| Challenger - Tampere | 07/17 15:30 | 25 | [289] Giovanni Fonio v Vit Kopriva [249] | 4-6,6-7 | |
| Challenger Troyes | 07/07 14:15 | 27 | [291] Giovanni Fonio v David Jorda Sanchis [438] | Retired | |
| Challenger Troyes | 07/05 10:20 | 26 | [291] Giovanni Fonio v Moez Echargui [279] | 6-3,6-2 | |
| Challenger Troyes | 07/03 15:30 | 25 | [236] Marco Trungelliti v Giovanni Fonio [291] | 4-6,2-6 | |
| Challenger - Modena | 06/27 12:50 | 25 | [227] Renzo Olivo v Giovanni Fonio [286] | 7-5,6-4 | |
| Challenger - Parma | 06/21 16:00 | 26 | [72] Albert Ramos-Vinolas v Giovanni Fonio [283] | 6-1,3-6,6-3 | |
| Challenger - Parma | 06/20 08:30 | 25 | Giovanni Fonio v Filippo Moroni | 6-3,6-2 | |
| Challenger - Bratislava | 06/12 13:15 | 19 | [285] Giovanni Fonio v Mohamed Safwat [474] | 6-3,3-6,2-6 | |
| Challenger - Bratislava | 06/12 10:20 | 45 | [276] Giovanni Fonio v Wilson Leite [490] | 7-6,6-1 | |
| Challenger - Vicenza | 05/29 08:30 | 19 | [276] Giovanni Fonio v Vitaliy Sachko [275] | 4-6,6-7 | |
| Challenger - Vicenza | 05/28 08:30 | 14 | [276] Giovanni Fonio v Alexander Weis [320] | 6-2,6-4 | |
| Challenger - Skopje | 05/24 09:00 | 26 | [273] Francisco Comesana v Giovanni Fonio [278] | 7-6,6-2 | |
| Challenger - Skopje | 05/22 11:10 | 25 | [421] Mili Poljicak v Giovanni Fonio [278] | 4-6,2-6 | |
| Challenger Francavilla | 05/12 10:00 | 26 | [291] Giovanni Fonio v Alejandro Tabilo [190] | 4-6,6-7 | |
| Challenger Francavilla | 05/09 12:20 | 25 | [286] Salvatore Caruso v Giovanni Fonio [291] | 6-3,1-6,6-7 | |
| Challenger Francavilla | 05/08 11:00 | 19 | [291] Giovanni Fonio v Alexander Weis [338] | 6-1,6-2 | |
| Challenger Francavilla | 05/07 09:00 | 14 | [304] Giovanni Fonio v Andrea Picchione [396] | 6-3,7-5 | |
| Challenger - Rím | 04/26 08:00 | 26 | [236] Marco Trungelliti v Giovanni Fonio [304] | 2-6,6-1,6-2 | |
| Challenger - Rím | 04/25 08:55 | 25 | [304] Giovanni Fonio v Mattia Bellucci [165] | 6-3,6-4 | |
| Challenger - Rím | 04/24 08:00 | 19 | Giovanni Fonio v Miguel Damas | 6-0,6-0 | |
| Challenger - Rím | 04/23 08:00 | 14 | Giovanni Fonio v Federico Salomone | 6-1,6-1 | |
| Challenger Roseto | 04/18 14:00 | 25 | [361] Francesco Forti v Giovanni Fonio [306] | 7-6,6-2 | |
| Challenger - Barletta | 04/02 09:10 | 14 | [328] Giovanni Fonio v Julian Ocleppo [394] | 7-6,6-7,1-6 | |
| Challenger - Sanremo | 03/29 12:00 | 26 | [108] Luca Van Assche v Giovanni Fonio [328] | 6-3,6-3 | |
| Challenger - Sanremo | 03/28 08:00 | 25 | [415] Gianmarco Ferrari v Giovanni Fonio [328] | 1-6,6-7 | |
| Challenger - Sanremo | 03/27 08:00 | 19 | [319] Moez Echargui v Giovanni Fonio [328] | 6-7,3-6 |
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).