| Challenger Todi | 08/18 19:00 | 28 | [334] Clement Tabur v Giovanni Fonio [322] | 7-5,4-6,6-3 | |
| Challenger Todi | 08/17 20:10 | 27 | Felix Gill v Giovanni Fonio | 3-6,4-6 | |
| Challenger Todi | 08/16 19:45 | 26 | [322] Giovanni Fonio v Ocleppo, Julian [448] | 6-3,6-7,6-4 | |
| Challenger Todi | 08/15 09:55 | 25 | [322] Giovanni Fonio v Orlando Luz [461] | 7-6,6-4 | |
| Cordenons, Italy | 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 | |
| Zug, Switzerland | 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 | |
| Parma II, Italy | 06/21 16:00 | 26 | [72] Albert Ramos-Vinolas v Giovanni Fonio [283] | 6-1,3-6,6-3 | |
| Parma II, Italy | 06/20 08:30 | 25 | Giovanni Fonio v Moroni, Filippo | 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 - Rome | 04/26 08:00 | 26 | [236] Marco Trungelliti v Giovanni Fonio [304] | 2-6,6-1,6-2 | |
| Challenger - Rome | 04/25 08:55 | 25 | [304] Giovanni Fonio v Mattia Bellucci [165] | 6-3,6-4 | |
| Challenger - Rome | 04/24 08:00 | 19 | Giovanni Fonio v Miguel Damas | 6-0,6-0 | |
| Challenger - Rome | 04/23 08:00 | 14 | Giovanni Fonio v Federico Salomone | 6-1,6-1 | |
| Challenger Roseto | 04/18 14:00 | 25 | [361] Forti, Francesco v Giovanni Fonio [306] | 7-6,6-2 | |
| Challenger - Barletta | 04/02 09:10 | 14 | [328] Giovanni Fonio v Ocleppo, Julian [394] | 7-6,6-7,1-6 |
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).