| Challenger - Vicenza | 05/29 12:40 | 26 | [297] Giovanni Fonio v Tomas Barrios Vera [157] | 5-7,4-6 | |
| Challenger - Vicenza | 05/28 13:00 | 25 | [227] Franco Agamenone v Giovanni Fonio [297] | 6-7,5-7 | |
| Challenger - Vicenza | 05/27 10:10 | 19 | [297] Giovanni Fonio v Arthur Gea [382] | 6-4,6-2 | |
| Challenger - Vicenza | 05/26 13:30 | 14 | [297] Giovanni Fonio v Ryan Seggerman [463] | 6-2,6-4 | |
| Challenger Skopje | 05/22 08:30 | 26 | [349] Gerard Campana Lee v Giovanni Fonio [302] | 6-1,6-2 | |
| Challenger Skopje | 05/21 08:45 | 25 | [302] Giovanni Fonio v Ryan Nijboer [428] | 6-2,6-1 | |
| Challenger Skopje | 05/21 08:30 | 25 | [302] Giovanni Fonio v Enrico Dalla Valle [257] | Cancelled | |
| ITF - M25 Reggio Emilia | 05/18 13:00 | 28 | Giovanni Fonio v Martin Klizan | 5-7,0-6 | |
| ITF - M25 Reggio Emilia | 05/17 10:00 | 27 | [268] Lorenzo Rottoli v Giovanni Fonio [304] | 4-6,3-6 | |
| ITF - M25 Reggio Emilia | 05/16 11:10 | 26 | Andrea Guerrieri v Giovanni Fonio | 7-6,2-6,2-6 | |
| ITF - M25 Reggio Emilia | 05/13 12:05 | 25 | [474] Federico Iannaccone v Giovanni Fonio [304] | 6-3,4-6,6-7 | |
| Challenger - Praag | 05/10 12:35 | 27 | [295] Jiri Vesely v Giovanni Fonio [304] | 2-6,6-1,6-4 | |
| Challenger - Praag | 05/09 12:15 | 26 | [304] Giovanni Fonio v Benjamin Bonzi [175] | 7-6,3-6,6-2 | |
| Challenger - Praag | 05/08 11:45 | 25 | [304] Giovanni Fonio v Geoffrey Blancaneaux [236] | 7-6,6-3 | |
| Challenger - Praag | 05/06 08:30 | 19 | Giovanni Fonio v Nikoloz Basilashvili | 4-6,2-6 | |
| Challenger - Praag | 05/05 08:30 | 14 | [301] Giovanni Fonio v Tibo Colson [453] | 6-2,6-0 | |
| Challenger - Tallahassee | 04/15 21:30 | 25 | Giovanni Fonio v Joel Schwaerzler | 2-6,4-6 | |
| Challenger - Sarasota | 04/09 20:30 | 25 | [195] Alexander Ritschard v Giovanni Fonio [304] | 6-3,6-1 | |
| Challenger - Sarasota | 04/08 16:50 | 19 | [304] Giovanni Fonio v Kyle Edmund [423] | 6-2,6-3 | |
| Challenger - Sarasota | 04/07 20:10 | 14 | Giovanni Fonio v Duarte Vale | 6-3,6-4 | |
| Challenger - Mexico City | 04/02 19:30 | 25 | [302] Giovanni Fonio v Nicolas Mejia [344] | 3-6,2-6 | |
| ITF - M25 Badalona | 03/20 09:00 | 25 | [283] Giovanni Fonio v Imanol L Morillo [481] | 4-6,5-7 | |
| Challenger - Szekesfehervar | 03/11 12:20 | 25 | [270] Giovanni Fonio v Zsombor Piros [106] | 3-6,2-6 | |
| Challenger - Tenerife - Kwal. | 02/25 11:55 | 14 | [430] Carlos Lopez Montagud v Giovanni Fonio [277] | 6-4,6-2 | |
| Challenger - Tenerife | 02/20 12:45 | 25 | [265] Adrian Andreev v Giovanni Fonio [277] | 4-6,6-3,7-5 | |
| Challenger - Tenerife | 02/19 10:00 | 19 | [277] Giovanni Fonio v Javier Barranco Cosano [302] | 6-4,3-6,6-4 | |
| Challenger - Tenerife | 02/18 10:00 | 14 | [277] Giovanni Fonio v Lorenzo Giustino [330] | 4-6,6-4,6-1 | |
| Challenger - Bengaluru | 02/12 10:30 | 25 | [277] Giovanni Fonio v Gauthier Onclin [252] | 4-6,6-1,6-7 | |
| Challenger Chennai | 02/07 09:30 | 26 | [270] Giovanni Fonio v Sumit Nagal [121] | 5-7,2-6 | |
| Challenger Chennai | 02/05 11:25 | 25 | [263] Maxime Janvier v Giovanni Fonio [270] | 4-6,6-3,5-7 |
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).