| Challenger Noumea | 01/03 09:40 | 26 | [400] Sinclair, Colin v Benoit Paire [117] | 6-4,2-6,2-6 | |
| Challenger Noumea | 01/02 02:40 | 25 | [452] Rubin Statham v Sinclair, Colin [400] | 7-6,4-6,4-6 | |
| Challenger Yokkaichi | 11/26 04:35 | 14 | [366] Sinclair, Colin v Ray Ho [173] | 3-6,5-7 | |
| Challenger Yokohama | 11/21 03:45 | 25 | [366] Sinclair, Colin v Mathys Erhard [342] | 3-6,2-6 | |
| Challenger Yokohama | 11/20 03:30 | 19 | [306] Giovanni Fonio v Sinclair, Colin [361] | 3-6,7-5,6-7 | |
| Challenger Yokohama | 11/19 07:55 | 14 | [484] Nathan Ponwith v Sinclair, Colin [361] | 3-6,6-7 | |
| Challenger Kobe | 11/12 01:00 | 14 | [387] James Trotter v Sinclair, Colin [361] | 6-4,7-5 | |
| Challenger Sydney | 10/30 04:05 | 25 | [353] Sinclair, Colin v Marc Polmans [160] | 4-6,2-6 | |
| Challenger - Shenzhen | 10/19 07:55 | 26 | [362] Sinclair, Colin v Lorenzo Giustino [290] | 3-6,4-6 | |
| Challenger - Shenzhen | 10/16 07:00 | 26 | [228] Evgeny Donskoy v Sinclair, Colin [362] | 6-2,3-6,4-6 | |
| Challenger - Shenzhen | 10/11 03:40 | 25 | [69] Thanasi Kokkinakis v Sinclair, Colin [347] | 6-2,3-6,6-3 | |
| Challenger - Shenzhen | 10/10 04:00 | 19 | [347] Sinclair, Colin v Tsung-Hao Huang [400] | 3-6,6-4,6-2 | |
| Challenger - Shenzhen | 10/09 09:35 | 14 | [347] Sinclair, Colin v Ray Ho [181] | 6-3,6-4 | |
| Shanghai, Chine | 10/02 06:30 | 14 | [346] Sinclair, Colin v Li Tu [201] | 6-4,4-6,3-6 | |
| Zhuhai, Chine | 09/19 03:00 | 14 | [340] Sinclair, Colin v Antoine Bellier [314] | 3-6,4-6 | |
| Challenger - Guangzhou | 09/13 06:15 | 26 | [347] Sinclair, Colin v Marc Polmans [167] | 4-6,4-6 | |
| Challenger - Guangzhou | 09/12 04:15 | 25 | [409] Luca Castelnuovo v Sinclair, Colin [347] | 1-6,2-6 | |
| Challenger Shanghai | 09/04 03:00 | 14 | [379] Sinclair, Colin v Matthew C Romios [186] | 4-6,4-6 | |
| Zhangjiagang, China | 09/01 03:00 | 27 | [254] Ricardas Berankis v Sinclair, Colin [379] | 7-5,6-7,6-1 | |
| Zhangjiagang, China | 08/31 02:30 | 26 | [417] Nam Hoang Ly v Sinclair, Colin [379] | 3-6,6-1,1-6 | |
| Zhangjiagang, China | 08/29 04:50 | 25 | [379] Sinclair, Colin v Kaichi Uchida [240] | 6-3,3-6,6-4 | |
| Zhangjiagang, China | 08/28 07:50 | - | Sinclair, Colin v Hanyi Liu | 6-1,3-6,6-7 | |
| Zhangjiagang, China | 08/27 07:10 | 45 | Sinclair, Colin v Kalovelonis, Markos | 6-4,6-1 | |
| Challenger Zhuhai | 08/23 05:15 | 26 | [434] Aliaksandr Liaonenka v Sinclair, Colin [384] | 7-6,6-3 | |
| Challenger Zhuhai | 08/22 03:25 | 25 | [384] Sinclair, Colin v Leo Borg [375] | 6-3,6-2 | |
| ITF M15 Caloundra | 08/05 02:55 | 28 | [379] Sinclair, Colin v Luke Saville [339] | 7-5,4-6,4-6 | |
| ITF M15 Caloundra | 08/04 00:00 | 27 | Hoole, Casey v Sinclair, Colin | 6-4,4-6,5-7 | |
| ITF M15 Caloundra | 08/03 01:45 | 26 | Pham, Derek v Sinclair, Colin | Retired | |
| ITF M15 Caloundra | 08/02 02:30 | 25 | Shepp, Anton v Sinclair, Colin | 2-6,5-7 | |
| Coupe Davis | 07/28 06:45 | 2 | Sinclair, Colin v Zaid Shelbaya | 6-1,6-0 |
Colin Sinclair (born December 19, 1994) is a Northern Mariana Islander tennis player.
He achieved a career best singles ranking of world No. 340 on 18 September 2023, and a career high doubles ranking of world No. 200 on 10 April 2023. He has won 2 singles titles on the ITF Futures Tour. Additionally, he has won 2 titles on ATP Challenger Tour and 7 titles on the ITF Futures Tour in doubles.
He represents his country in Davis Cup as part of the Pacific Oceania team since 2017 and has a career record of 18–5 (13–3 in singles, 5–2 in doubles) in the competition. He has been coached by Jeff Race, Ian Malpass, and Silviu Tanasoiu.