| Challenger Kobe | 11/15 05:05 | 25 | [84] Christopher O'Connell v Colin Sinclair [363] | 6-7,7-6,7-6 | |
| Challenger Kobe | 11/14 01:00 | 19 | [484] James Trotter v Colin Sinclair [366] | 4-6,1-6 | |
| Challenger Kobe | 11/13 01:00 | 14 | Ryotaro Taguchi v Colin Sinclair | 6-7,6-7 | |
| Challenger Sydney | 10/31 08:05 | 25 | [361] Colin Sinclair v Aleksandar Vukic [145] | 6-7,2-6 | |
| Challenger Sydney | 10/29 23:30 | 26 | Colin Sinclair v Jordan Smith | Cancelled | |
| Challenger Playford | 10/26 23:30 | 26 | [266] Max Purcell v Colin Sinclair [387] | 7-5,6-1 | |
| Challenger Playford | 10/25 03:00 | 25 | [387] Colin Sinclair v Aleksandar Vukic [145] | 6-4,3-6,6-2 | |
| ITF M25 Cairns | 10/14 00:00 | 27 | [447] Tristan Schoolkate v Colin Sinclair [463] | 6-4,6-4 | |
| ITF M25 Cairns | 10/13 00:00 | 26 | Colin Sinclair v Blake Ellis | 7-6,3-6,7-6 | |
| ITF M25 Cairns | 10/12 00:00 | 25 | Moerani Bouzige v Colin Sinclair | 5-7,2-6 | |
| ITF M25 Cairns | 10/09 05:00 | 29 | Alex Bolt v Colin Sinclair | 6-3,6-2 | |
| ITF M25 Cairns | 10/08 01:00 | 28 | [493] Blake Ellis v Colin Sinclair [450] | 6-4,3-6,2-6 | |
| ITF M25 Cairns | 10/07 01:00 | 27 | Colin Sinclair v Mitchell Harper | 6-4,4-6,6-2 | |
| ITF M25 Cairns | 10/06 00:00 | 26 | [440] Tristan Schoolkate v Colin Sinclair [450] | 4-6,4-6 | |
| ITF M25 Cairns | 10/04 04:15 | 25 | Jeremy Jin v Colin Sinclair | 5-7,6-7 | |
| ITF M25 Darwin | 09/22 05:30 | 26 | Colin Sinclair v James McCabe | 6-7,4-6 | |
| ITF M25 Darwin | 09/20 05:30 | 25 | Aaron Addison v Colin Sinclair | 3-6,6-7 | |
| ITF M25 Darwin | 09/14 08:05 | 25 | Philip Sekulic v Colin Sinclair | 6-7,7-6,6-3 | |
| UTR Pro Tennis Series Marrara | 09/10 07:00 | - | Colin Sinclair v Joshua Charlton | 6-2,6-4 | |
| UTR Pro Tennis Series Marrara | 09/09 11:07 | - | [476] Colin Sinclair v Aaron Addison [436] | 6-3,6-3 | |
| UTR Pro Tennis Series Marrara | 09/08 08:30 | - | Colin Sinclair v Matt Hulme | 7-6,5-2 | |
| UTR Pro Tennis Series Marrara | 09/05 05:30 | - | Tomislav Papac v Colin Sinclair | 5-7,1-6 | |
| ITF M15 Anseong | 08/18 01:00 | 26 | Colin Sinclair v Sanhui Shin | 4-6,5-7 | |
| ITF M15 Anseong | 08/17 03:10 | 25 | Colin Sinclair v Guen Jun Kim | 7-5,6-2 | |
| Davis Kupa | 08/13 05:05 | 2 | [344] Nam Hoang Ly v Colin Sinclair [483] | 6-2,3-6,6-3 | |
| Davis Kupa | 08/12 04:25 | 2 | Colin Sinclair v Ammar Faleh Alhogbani | 6-4,6-0 | |
| Davis Kupa | 08/11 07:25 | 2 | Colin Sinclair v Abdulla Al Marzouqi | 6-2,6-0 | |
| Davis Kupa | 08/10 03:40 | 2 | Colin Sinclair v Ali Yazdani | 6-2,6-3 | |
| ITF M15 Caloundra | 07/28 01:05 | 26 | Mitchell Harper v Colin Sinclair | 3-6,6-2,6-1 | |
| ITF M15 Caloundra | 07/27 03:55 | 25 | Mikal Statham v Colin Sinclair | 2-6,0-6 |
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.