| Challenger - Little Rock | 06/04 15:00 | 25 | [277] Collin Altamirano v Alexander Sarkissian [345] | 6-3,6-1 | |
| Challenger - Jerusalem | 05/22 07:00 | 25 | [478] Edan Leshem v Collin Altamirano [278] | 1-6,6-1,6-4 | |
| Challenger - Savannah | 05/02 15:00 | 26 | [287] Collin Altamirano v Aleksandar Vukic [354] | Retired | |
| Challenger - Savannah | 05/01 18:15 | 25 | [168] Noah Rubin v Collin Altamirano [287] | 6-2,2-6,2-6 | |
| Challenger - Savannah | 04/29 17:25 | 24 | [287] Collin Altamirano v Alen Avidzba [380] | 6-0,7-6 | |
| Challenger - Tallahassee | 04/24 16:30 | 25 | [290] Collin Altamirano v Nino Serdarusic [244] | 3-6,6-2,6-7 | |
| Challenger - Tallahassee | 04/22 18:05 | 24 | [355] Ryan Shane v Collin Altamirano [290] | 4-6,6-7 | |
| Challenger - Sarasota | 04/16 19:30 | 25 | [128] Peter Polansky v Collin Altamirano [294] | 6-1,6-4 | |
| Challenger - Sarasota | 04/15 19:45 | 24 | [224] Evgeny Karlovskiy v Collin Altamirano [294] | 7-6,4-6,4-6 | |
| Challenger - Taipei | 04/08 09:40 | 24 | [295] Collin Altamirano v Chien-Hsun Lo [411] | 5-7,7-5,3-6 | |
| Challenger - Monterrey | 04/01 23:05 | 24 | [391] Carlos G-Herrera v Collin Altamirano [293] | 6-1,6-4 | |
| Challenger - St Brieuc | 03/25 13:20 | 24 | [294] Collin Altamirano v Lucas Miedler [270] | 3-6,3-6 | |
| Challenger - Drummondville | 03/13 23:20 | 25 | [95] Ricardas Berankis v Collin Altamirano [297] | 6-4,7-5 | |
| Challenger - Drummondville | 03/12 15:25 | 24 | [478] Manuel Guinard v Collin Altamirano [297] | 4-6,3-6 | |
| Challenger - Chennai | 02/06 04:30 | 25 | [222] Gianluca Mager v Collin Altamirano [296] | 6-3,6-1 | |
| Challenger - Chennai | 02/05 06:30 | 24 | [387] Kaito Uesugi v Collin Altamirano [296] | 6-1,3-6,6-7 | |
| Challenger - Newport Beach | 01/25 22:55 | 27 | [231] Donald Young v Collin Altamirano [309] | 6-2,6-1 | |
| Challenger - Newport Beach | 01/24 21:50 | 26 | [309] Collin Altamirano v Dustin Brown [223] | 7-6,6-2 | |
| Challenger - Newport Beach | 01/23 22:20 | 25 | [309] Collin Altamirano v Victor Estrella Burgos [305] | 7-5,6-2 | |
| Challenger - Newport Beach | 01/21 18:00 | 166 | [309] Collin Altamirano v Alafia Ayeni [444] | Cancelled | |
| Challenger - Pune | 11/20 09:50 | 25 | Collin Altamirano v Lucas Gerch | 3-6,1-6 | |
| Challenger - Bangalore | 11/13 05:30 | 25 | [286] Collin Altamirano v Sasi Kumar Mukund [416] | 6-7,3-6 | |
| Challenger - Charlottesville | 10/30 22:10 | 25 | [373] Marcos Giron v Collin Altamirano [283] | 6-4,6-4 | |
| Challenger - Calgary | 10/18 01:20 | 26 | [298] Collin Altamirano v Filip Peliwo [194] | 7-5,6-7,1-6 | |
| Challenger - Calgary | 10/15 18:40 | 25 | [178] Jay Clarke v Collin Altamirano [298] | 5-7,0-6 | |
| Challenger - Fairfield | 10/10 22:20 | 26 | [155] Alex Bolt v Collin Altamirano [306] | 7-6,6-7,7-6 | |
| Challenger - Fairfield | 10/08 19:00 | 25 | [306] Collin Altamirano v Daniel Evans [208] | Retired | |
| Challenger - Stockton | 09/29 22:20 | 45 | Collin Altamirano v Isaiah Strode | 4-6,0-6 | |
| US Open | 08/27 16:30 | 23 | [345] Collin Altamirano v Ugo Humbert [139] | 3-6,6-7,3-6 | |
| US Open | 08/24 18:00 | 46 | [117] Lorenzo Sonego v Collin Altamirano [345] | 4-6,6-7 |