| Challenger de Yokkaichi | 11/27 04:45 | 25 | [285] Giovanni Fonio v Kalin Ivanovski [305] | 4-6,7-6,7-6 | |
| Challenger de Yokohama | 11/24 04:05 | 27 | [98] Yosuke Watanuki v Giovanni Fonio [299] | 3-6,6-2,6-1 | |
| Challenger de Yokohama | 11/23 05:15 | 26 | [299] Giovanni Fonio v Leandro Riedi [208] | 4-6,7-6,6-4 | |
| Challenger de Yokohama | 11/21 02:45 | 25 | [337] August Holmgren v Giovanni Fonio [299] | 4-6,1-6 | |
| Challenger de Yokohama | 11/20 03:30 | 19 | [306] Giovanni Fonio v Colin Sinclair [361] | 3-6,7-5,6-7 | |
| Challenger de Yokohama | 11/19 05:10 | 14 | [306] Giovanni Fonio v Hiroki Moriya [435] | 5-7,6-3,6-4 | |
| Challenger de Kobe | 11/14 05:00 | 25 | [306] Giovanni Fonio v Shintaro Mochizuki [137] | 6-4,2-6,3-6 | |
| Challenger de Kobe | 11/13 02:55 | 19 | [306] Giovanni Fonio v Shinji Hazawa [315] | 6-3,6-7,6-1 | |
| Challenger de Kobe | 11/12 05:25 | 14 | [306] Giovanni Fonio v Hiroki Moriya [428] | 7-5,6-2 | |
| Challenger de Matsuyama | 11/07 03:45 | 25 | [155] Sho Shimabukuro v Giovanni Fonio [306] | 5-7,6-4,6-4 | |
| ITF M25 Santa Margarita | 10/25 08:00 | 26 | [306] Giovanni Fonio v Giovanni Oradini [396] | 6-3,3-6,2-6 | |
| ITF M25 Santa Margarita | 10/24 09:00 | 25 | Giovanni Fonio v Giammarco Gandolfi | 6-2,6-3 | |
| ITF M25 Santa Margarita | 10/19 09:20 | 27 | [304] Giovanni Fonio v Nerman Fatic [224] | 6-7,4-6 | |
| ITF M25 Santa Margarita | 10/18 07:55 | 26 | Giovanni Fonio v Luciano Carraro | 6-4,6-2 | |
| ITF M25 Santa Margarita | 10/17 13:25 | 25 | Giovanni Fonio v Andrea Gola | 7-6,6-2 | |
| ITF M25 Santa Margarita | 10/12 08:00 | 27 | [459] Marcello Serafini v Giovanni Fonio [311] | 7-6,6-3 | |
| ITF M25 Santa Margarita | 10/11 09:20 | 26 | Niccolo Catini v Giovanni Fonio | 2-6,3-6 | |
| ITF M25 Santa Margarita | 10/10 09:45 | 25 | Gabriele Piraino v Giovanni Fonio | 6-7,0-6 | |
| Challenger de Lisboa | 10/01 10:45 | 14 | [314] Giovanni Fonio v Luka Mikrut [411] | 6-7,3-6 | |
| Challenger de Braga | 09/25 11:40 | 19 | [270] Oriol Roca Batalla v Giovanni Fonio [305] | 6-3,6-7,6-1 | |
| Challenger de Braga | 09/24 14:10 | 14 | Pedro Araujo v Giovanni Fonio | 1-6,7-5,5-7 | |
| Challenger Sibiu | 09/21 08:40 | 26 | [207] Duje Ajdukovic v Giovanni Fonio [305] | 4-6,6-3,6-2 | |
| Challenger Sibiu | 09/20 10:20 | 25 | [305] Giovanni Fonio v Cezar Cretu [355] | 7-6,6-3 | |
| Challenger de Génova | 09/04 11:50 | 25 | [289] Giovanni Fonio v Franco Agamenone [193] | 6-7,6-4,3-6 | |
| Challenger de Como | 08/29 10:35 | 19 | [289] Giovanni Fonio v Valentin Royer [335] | 4-6,4-6 | |
| Challenger de Como | 08/28 13:40 | 14 | [289] Giovanni Fonio v David Jorda Sanchis [373] | 4-6,6-3,7-5 | |
| Challenger de Augsburgo | 08/22 08:00 | 25 | [294] Oliver Crawford v Giovanni Fonio [288] | 6-2,6-3 | |
| Challenger de Todi | 08/18 19:00 | 28 | [334] Clement Tabur v Giovanni Fonio [322] | 7-5,4-6,6-3 | |
| Challenger de Todi | 08/17 20:10 | 27 | Felix Gill v Giovanni Fonio | 3-6,4-6 | |
| Challenger de Todi | 08/16 19:45 | 26 | [322] Giovanni Fonio v Julian Ocleppo [448] | 6-3,6-7,6-4 |
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).