| ITF Korea F5 | 08/26 03:00 | 29 | [381] Ji Sung Nam v Makoto Ochi [376] | 6-4,6-1 | |
| ITF Korea F5 | 08/25 01:00 | 28 | [368] Cheong-Eui Kim v Ji Sung Nam [381] | 2-6,3-6 | |
| ITF Korea F5 | 08/24 01:15 | 27 | Ji Sung Nam v Ji Hoon Son | 6-4,6-2 | |
| ITF Korea F5 | 08/23 04:45 | 26 | Ji Sung Nam v Edward Bourchier | 6-2,6-2 | |
| ITF Korea F5 | 08/21 01:00 | 25 | Ji Sung Nam v Seong Jae Han | 6-1,6-0 | |
| Challenger Gwangju | 08/19 01:55 | 29 | [284] Maverick Banes v Ji Sung Nam [439] | 6-3,4-6,6-4 | |
| Challenger Gwangju | 08/18 02:00 | 28 | [239] Alexander Bublik v Ji Sung Nam [439] | 6-7,5-7 | |
| Challenger Gwangju | 08/17 03:30 | 27 | [299] Akira Santillan v Ji Sung Nam [439] | 2-6,3-6 | |
| Challenger Gwangju | 08/16 06:00 | 26 | [498] Zihao Xia v Ji Sung Nam [439] | 2-6,3-6 | |
| Challenger Gwangju | 08/14 08:20 | 25 | [439] Ji Sung Nam v Henri Laaksonen [126] | 6-1,6-1 | |
| Challenger Gwangju Qual | 08/13 01:00 | 54 | Ji Sung Nam v Sami Reinwein | 6-2,6-4 | |
| Challenger Gwangju Qual | 08/12 03:25 | 46 | Ji Sung Nam v Vasko Mladenov | 6-3,6-3 | |
| ITF China F10 | 07/13 06:15 | 27 | Ji Sung Nam v Rigele Te | 3-6,4-6 | |
| ITF China F10 | 07/11 03:00 | 26 | Maverick Banes v Ji Sung Nam | 1-6,2-6 | |
| ITF China F10 | 07/09 05:00 | 25 | Seong Chan Hong v Ji Sung Nam | 3-6,3-6 | |
| ITF China F9 | 07/02 09:10 | 25 | Ji Sung Nam v Runhao Hua | 6-7,4-6 | |
| ITF Korea F3 | 06/24 05:00 | 29 | Yunseong Chung v Ji Sung Nam | 6-1,6-3 | |
| ITF Korea F3 | 06/23 03:55 | 28 | Takuto Niki v Ji Sung Nam | 3-6,6-4,1-6 | |
| ITF Korea F3 | 06/23 01:00 | - | Takuto Niki v Ji Sung Nam | 3-6,6-4,1-6 | |
| ITF Korea F3 | 06/22 05:10 | 27 | Ji Sung Nam v Cheong-Eui Kim | 6-7,6-4,6-3 | |
| ITF Korea F3 | 06/21 01:00 | 26 | Ji Sung Nam v Jea Moon Lee | 7-5,6-3 | |
| ITF Korea F3 | 06/19 08:15 | 25 | Ji Sung Nam v Mitchell Thomas McDaniels | 6-0,6-1 | |
| ITF Korea F2 | 06/17 04:00 | 29 | Ji Sung Nam v Yunseong Chung | 4-6,3-6 | |
| ITF Korea F2 | 06/16 01:00 | 28 | Cheong-Eui Kim v Ji Sung Nam | 4-6,2-6 | |
| ITF Korea F2 | 06/15 01:00 | 27 | Seong Chan Hong v Ji Sung Nam | 5-7,3-6 | |
| ITF Korea F2 | 06/14 01:00 | 26 | Jea Moon Lee v Ji Sung Nam | 2-6,0-6 | |
| ITF Korea F2 | 06/13 06:50 | 25 | Young Seok Kim v Ji Sung Nam | 6-7,0-6 | |
| ITF Korea F1 | 06/08 02:00 | 27 | Ji Sung Nam v Yong-Kyu Lim | 1-6,2-6 | |
| ITF Korea F1 | 06/07 03:00 | 26 | Ji Sung Nam v Jung-Woong Na | Retired | |
| ITF Korea F1 | 06/06 02:15 | 25 | Ji Sung Nam v Daniel Yoo | 6-4,6-3 |
Nam Ji-sung (born 15 August 1993) is a South Korean tennis player. He has a career high ATP singles ranking of world No. 236 achieved on 12 August 2019. He also has a career high ATP doubles ranking of No. 102 achieved on 3 February 2020.
Playing for South Korea in Davis Cup, Nam has a W/L record of 3–7.