| Challenger Sarasota | 04/12 17:30 | 27 | [150] Gabriel Diallo v Thanasi Kokkinakis [106] | 6-7,6-4,6-7 | |
| Challenger Sarasota | 04/11 16:45 | 26 | [150] Gabriel Diallo v Tristan Boyer [196] | 6-7,6-3,6-4 | |
| Challenger Sarasota | 04/09 19:55 | 25 | [150] Gabriel Diallo v Federico Agustin Gomez [332] | 7-6,7-6 | |
| ATP Houston | 03/30 16:00 | 14 | [133] Gabriel Diallo v Mitchell Krueger [282] | 6-7,6-7 | |
| ATP Miami | 03/18 15:00 | 14 | [133] Gabriel Diallo v Sumit Nagal [97] | 6-7,2-6 | |
| ATP Delray Beach | 02/12 23:00 | 25 | [136] Gabriel Diallo v Nuno Borges [46] | 4-6,6-7 | |
| ATP Delray Beach | 02/11 19:35 | 19 | [138] Gabriel Diallo v Zachary Svajda [145] | 4-6,6-4,3-6 | |
| ATP Delray Beach | 02/10 20:05 | 14 | [138] Gabriel Diallo v Valentin Vacherot [173] | 6-4,6-4 | |
| Davis Cup | 02/03 21:40 | 168 | [132] Gabriel Diallo v Seongchan Hong [224] | 7-5,4-6,6-1 | |
| Davis Cup | 02/02 21:00 | 168 | Gabriel Diallo v Soonwoo Kwon | 6-4,6-4 | |
| Challenger Quimper | 01/25 18:25 | 26 | [157] Harold Mayot v Gabriel Diallo [135] | 7-6,7-6 | |
| Challenger Quimper | 01/23 19:30 | 25 | [156] Elias Ymer v Gabriel Diallo [135] | 5-7,2-6 | |
| Australian Open | 01/12 00:35 | 19 | [107] David Goffin v Gabriel Diallo [136] | 3-6,6-3,6-2 | |
| Australian Open | 01/10 23:00 | 15 | [234] Pierre-Hugues Herbert v Gabriel Diallo [136] | 6-4,4-6,6-7 | |
| Australian Open | 01/09 00:45 | 14 | [162] Pablo Llamas Ruiz v Gabriel Diallo [136] | 6-7,1-6 | |
| Challenger Canberra | 01/05 04:40 | 28 | [77] Dominik Koepfer v Gabriel Diallo [139] | 6-7,7-5,6-3 | |
| Challenger Canberra | 01/04 00:40 | 27 | [139] Gabriel Diallo v Matteo Gigante [181] | 7-6,6-2 | |
| Challenger Canberra | 01/03 00:30 | 26 | [201] Rudolf Molleker v Gabriel Diallo [139] | 6-7,3-6 | |
| Challenger Canberra | 01/01 00:25 | 25 | [139] Gabriel Diallo v Juan Manuel Cerundolo [120] | 4-6,6-3,6-0 | |
| Davis Cup | 11/21 16:40 | 27 | [139] Gabriel Diallo v Otto Virtanen [171] | 4-6,5-7 | |
| Challenger Drummondville | 11/14 15:00 | 25 | Gabriel Diallo v Michael Vrbensky | Cancelled | |
| Challenger Calgary | 11/11 22:30 | 28 | Dominik Koepfer v Gabriel Diallo | Walkover | |
| Challenger Calgary | 11/10 23:00 | 27 | [133] Gabriel Diallo v Aziz Dougaz [242] | 6-3,6-2 | |
| Challenger Calgary | 11/09 22:45 | 26 | [133] Gabriel Diallo v Joao Sousa [276] | 5-7,7-5,6-3 | |
| Challenger Calgary | 11/08 04:30 | 25 | [133] Gabriel Diallo v Andrew Paulson [302] | 4-6,7-6,6-4 | |
| Challenger Brest | 10/24 11:15 | 25 | [132] Radu Albot v Gabriel Diallo [133] | 6-7,6-2,6-3 | |
| Challenger Brest | 10/23 09:00 | 19 | [133] Gabriel Diallo v Geoffrey Blancaneaux [244] | 6-4,4-6,7-6 | |
| Challenger Brest | 10/22 08:00 | 14 | Gabriel Diallo v Niels Villard | 7-6,6-1 | |
| Challenger Bratislava | 10/15 13:00 | 29 | [164] Gabriel Diallo v Joris De Loore [188] | 6-0,7-5 | |
| Challenger Bratislava | 10/14 14:10 | 28 | [164] Gabriel Diallo v Martin Damm [330] | 7-6,6-2 |