| 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 Qual | 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 |
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).