| ITF M15 Tokyo | 07/03 02:30 | - | [295] Colin Sinclair v Yusuke Kusuhara [315] | 7-6,3-6,6-7 | |
| ITF M15 Tokyo | 07/01 06:51 | - | Colin Sinclair v Naoya Honda | 6-1,6-4 | |
| ITF M15 Maanshan | 06/28 05:39 | - | Luca Castelnuovo v Colin Sinclair | 7-6,6-4 | |
| ITF M15 Maanshan | 06/27 02:00 | - | [471] Kokoro Isomura v Colin Sinclair [294] | 3-6,7-6,3-6 | |
| ITF M15 Maanshan | 06/26 07:03 | - | Colin Sinclair v Mitsuki Wei Kang Leong | 6-3,7-6 | |
| ITF M15 Maanshan | 06/25 02:00 | - | Yuquan Jin v Colin Sinclair | 7-5,4-6,3-6 | |
| ITF M25 Luzhou | 06/18 02:00 | - | [297] Colin Sinclair v Tsung-Hao Huang [283] | 5-7,5-7 | |
| ITF M15 Harmon | 06/13 02:50 | - | Colin Sinclair v Hikaru Shiraishi | 2-6,6-7 | |
| ITF M15 Harmon | 06/12 01:30 | - | Colin Sinclair v Geun Jun Kim | 6-4,6-0 | |
| ITF M15 Harmon | 06/11 03:00 | - | Colin Sinclair v Jumpei Yamasaki | 6-3,5-7,6-3 | |
| Challenger Guangzhou | 04/28 02:00 | 19 | [389] Andre Ilagan v Colin Sinclair [279] | 6-3,7-5 | |
| Challenger Guangzhou | 04/27 02:00 | 14 | [279] Colin Sinclair v Jake Delaney [479] | 6-3,3-6,6-4 |
Colin Sinclair (born December 19, 1994) is an American tennis player representing the Northern Mariana Islands.
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 four doubles titles on the ATP Challenger Tour and eight doubles titles on the ITF Tour. Additionally, he has won three singles ITF titles.
He represents the Northern Mariana Islands 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.