| Challenger Surbiton | 06/06 15:15 | 25 | [140] Liam Broady v Gabriel Diallo [146] | 4-6,4-6 | |
| French Open | 05/23 16:45 | 14 | [147] Timofey Skatov v Gabriel Diallo [146] | 6-4,7-6 | |
| Challenger Busan | 05/13 06:00 | 28 | [87] Max Purcell v Gabriel Diallo [162] | 6-4,7-5 | |
| Challenger Busan | 05/12 06:35 | 27 | [80] Jordan Thompson v Gabriel Diallo [162] | 3-6,5-7 | |
| Challenger Busan | 05/11 06:40 | 26 | [328] Yunseong Chung v Gabriel Diallo [162] | 6-7,6-7 | |
| Challenger Busan | 05/09 02:00 | 25 | [167] Jisung Nam v Gabriel Diallo [162] | 3-6,3-6 | |
| Challenger Gwangju | 05/01 08:05 | 25 | [141] Rinky Hijikata v Gabriel Diallo [169] | 6-2,6-4 | |
| Challenger Seoul | 04/27 06:45 | 26 | [169] Gabriel Diallo v Christopher Eubanks [90] | 6-2,3-6,2-6 | |
| Challenger Seoul | 04/24 06:45 | 25 | [169] Gabriel Diallo v Yu Hsiou Hsu [188] | 6-2,6-3 | |
| Challenger Sarasota | 04/14 18:10 | 27 | [113] Daniel Altmaier v Gabriel Diallo [178] | Retired | |
| Challenger Sarasota | 04/12 19:20 | 26 | [178] Gabriel Diallo v Mitchell Krueger [262] | 6-2,6-4 | |
| Challenger Sarasota | 04/11 17:00 | 25 | [158] Facundo D Acosta v Gabriel Diallo [178] | 6-3,2-6,6-7 | |
| Challenger Lille | 03/31 16:35 | 27 | [212] Gabriel Diallo v Jurij Rodionov [131] | 6-2,5-7,1-6 | |
| Challenger Lille | 03/30 17:00 | 26 | [212] Gabriel Diallo v Richard Berankis [235] | 6-3,7-5 | |
| Challenger Lille | 03/29 11:15 | 25 | [146] Hugo Grenier v Gabriel Diallo [212] | 6-4,4-6,2-6 | |
| Challenger Biel | 03/24 15:50 | 27 | [161] Liam Broady v Gabriel Diallo [212] | 3-6,7-5,6-3 | |
| Challenger Biel | 03/23 13:55 | 26 | Kirill Kivattsev v Gabriel Diallo | 2-6,3-6 | |
| Challenger Biel | 03/22 13:55 | 25 | Dylan Dietrich v Gabriel Diallo | 6-4,1-6,4-6 | |
| ITF M25 Montreal | 03/19 15:00 | 29 | [213] Gabriel Diallo v Henri Squire [325] | 7-6,6-3 | |
| ITF M25 Montreal | 03/18 15:00 | 28 | [213] Gabriel Diallo v Strong Kirchheimer [437] | 6-2,7-6 | |
| ITF M25 Montreal | 03/18 14:00 | 26 | Gabriel Diallo v Roy Smith | Cancelled | |
| ITF M25 Montreal | 03/17 14:00 | 27 | Gabriel Diallo v Tibo Colson | 6-2,7-5 | |
| ITF M25 Montreal | 03/16 15:25 | 26 | Gabriel Diallo v Aurel Ciocanu | 6-3,6-3 | |
| ITF M25 Montreal | 03/14 18:10 | 25 | Gabriel Diallo v Toby Kodat | 6-1,6-7,7-6 | |
| Challenger Puerto Vallarta | 03/08 01:30 | 25 | [309] Yuta Shimizu v Gabriel Diallo [213] | 4-6,6-3,7-6 | |
| ATP Dallas | 02/08 18:00 | 25 | [102] Emilio Gomez v Gabriel Diallo [211] | 6-4,6-7,7-6 | |
| ATP Dallas | 02/06 19:35 | 19 | [195] Brandon Holt v Gabriel Diallo [211] | 7-6,7-6 | |
| ATP Dallas | 02/05 23:05 | 14 | Antonio M-Hidalgo v Gabriel Diallo | 4-6,3-6 | |
| Challenger Cleveland | 02/03 19:35 | 27 | [106] Emilio Gomez v Gabriel Diallo [221] | 7-6,4-6,7-5 | |
| Challenger Cleveland | 02/01 17:50 | 26 | [229] Mitchell Krueger v Gabriel Diallo [221] | 7-6,1-6,1-6 |