Stadium: Court 1 Round: 25 Ground: Hardcourt outdoor
| Challenger Kobe | 2018/11/10 06:00 | Gao, Xin v Kazuki Nishiwaki | 6-4,6-4 |
| Nanchang, China | 2019/04/22 04:35 | Patael, Ben v Gao, Xin | 6-1,6-4 |
| Anning, China | 2019/04/15 10:10 | Gao, Xin v Viola, Matteo | 3-6,1-6 |
| Zhangjiagang, China | 2019/03/18 05:40 | Gao, Xin v Wu, Di | 5-7,4-6 |
| Challenger Zhuhai | 2019/03/04 07:05 | Gao, Xin v Alex Molcan | 5-7,4-6 |
| ITF M25 Glasgow | 2019/02/18 18:05 | Gao, Xin v Alexander Ritschard | 4-6,2-6 |
| ITF M25 Glasgow | 2019/02/18 11:40 | Gao, Xin v Paris, Joshua | 7-6,3-6,10-8 |
| Barnstaple, Singles Qualifying M-ITF-GBR-01A | 2019/02/11 10:00 | Gao, Xin v Cash, Julian | 5-7,1-6 |
| Challenger Canberra | 2019/01/07 06:50 | Verbeek, Sem v Gao, Xin | 1-6,7-6,6-3 |
| Matsuyama, Singles M-ITF-JPN-06A | 2019/04/10 07:40 | Rinky Hijikata v Kazuki Nishiwaki | 6-3,6-4 |
| ITF - M15 Kashiwa | 2019/04/01 06:00 | Kuan-Yi Lee v Kazuki Nishiwaki | 6-4,6-4 |
| ITF - M15 Kashiwa | 2019/04/01 00:00 | Daisuke Sumizawa v Kazuki Nishiwaki | 6-2,2-6,8-10 |
| ITF - M15 Tsukuba | 2019/03/27 01:00 | Makoto Ochi v Kazuki Nishiwaki | 6-3,6-1 |
| Kofu, Qualifications Simples M-ITF-JPN-03A | 2019/03/20 05:10 | Veldheer, Mick v Kazuki Nishiwaki | 4-6,6-1,6-4 |
| ITF - M15 Sharm El Sheikh | 2019/02/18 12:15 | Kazuki Nishiwaki v Giorgio Ricca | 7-5,6-7,6-10 |
| ITF - M15 Sharm El Sheikh | 2019/02/18 07:30 | Kazuki Nishiwaki v Mathys Erhard | 6-0,6-1 |
| ITF M15 Anning | 2019/01/12 05:05 | Kazuki Nishiwaki v Velotti, Agustin | 6-7,2-6 |