| Challenger Launceston | 01/30 23:00 | 26 | [265] Maverick Banes v Lorenzo Giustino [227] | 6-7,3-6 | |
| Challenger Launceston | 01/30 02:40 | 25 | [278] Yunseong Chung v Lorenzo Giustino [227] | 3-6,7-6,3-6 | |
| Challenger Burnie | 01/24 03:30 | 26 | [435] Harry Bourchier v Lorenzo Giustino [222] | 7-6,7-6 | |
| Challenger Burnie | 01/21 23:00 | 25 | [277] Yunseong Chung v Lorenzo Giustino [222] | 2-6,3-6 | |
| Australian Open | 01/09 00:35 | 44 | [223] Lorenzo Giustino v Yuichi Sugita [146] | 6-7,6-2,4-6 | |
| Challenger Noumea | 12/31 02:25 | 24 | [259] Lorenzo Giustino v Thai-Son Kwiatkowski [417] | 2-6,3-6 | |
| Challenger Montevideo | 11/09 18:00 | 27 | [205] Lorenzo Giustino v Guido Pella [65] | Retired | |
| Challenger Montevideo | 11/07 18:40 | 26 | [260] Pedro Cachin v Lorenzo Giustino [205] | 1-6,3-6 | |
| Challenger Montevideo | 11/05 17:00 | 25 | [205] Lorenzo Giustino v Thomaz Bellucci [247] | 6-3,6-3 | |
| Challenger Guayaquil | 10/29 18:00 | 25 | [119] Juan Ignacio Londero v Lorenzo Giustino [206] | 6-2,6-4 | |
| Challenger Barcelona | 10/12 09:30 | 27 | [174] Pedro Martinez v Lorenzo Giustino [218] | 6-2,7-5 | |
| Challenger Barcelona | 10/11 09:30 | 26 | [218] Lorenzo Giustino v Nicola Kuhn [342] | 6-4,4-6,6-1 | |
| Challenger Barcelona | 10/10 10:00 | 25 | [341] Jordi Samper-Montana v Lorenzo Giustino [218] | 4-6,4-6 | |
| Challenger Florence | 10/05 13:45 | 27 | [117] Pablo Andujar v Lorenzo Giustino [230] | 6-4,6-7,6-3 | |
| Challenger Florence | 10/04 08:30 | 26 | [276] Kevin Krawietz v Lorenzo Giustino [230] | 2-6,4-6 | |
| Challenger Florence | 10/02 13:55 | 25 | Lorenzo Giustino v Francesco Forti | 6-2,7-6 | |
| Challenger Florence | 10/02 08:00 | 25 | Lorenzo Giustino v Simone Bolelli | Cancelled | |
| Challenger Biella | 09/18 11:45 | 25 | Roberto Carballes Baena v Lorenzo Giustino | 6-3,6-4 | |
| Challenger Szczecin | 09/13 12:45 | 26 | [189] Alexey Vatutin v Lorenzo Giustino [237] | 6-7,6-1,6-0 | |
| Challenger Szczecin | 09/11 16:00 | 25 | [237] Lorenzo Giustino v Dustin Brown [204] | 6-7,6-1,7-6 | |
| Challenger Sevilla | 09/05 09:00 | 26 | [255] Lorenzo Giustino v Sergio Gutierrez-Ferrol [162] | 7-5,3-6,3-6 | |
| Challenger Sevilla | 09/04 08:30 | 25 | [255] Lorenzo Giustino v Federico Gaio [242] | 6-4,6-2 | |
| Challenger Como | 08/29 11:45 | 26 | [223] Viktor Galovic v Lorenzo Giustino [255] | 4-6,7-5,7-5 | |
| Challenger Como | 08/28 08:00 | 25 | [255] Lorenzo Giustino v Stephane Robert [136] | 6-2,6-1 | |
| US Open | 08/24 15:00 | 46 | [255] Lorenzo Giustino v Dennis Novak [140] | 5-7,4-6 | |
| US Open | 08/23 15:00 | 45 | [232] Danilo Petrovic v Lorenzo Giustino [255] | 2-6,6-4,3-6 | |
| US Open | 08/21 17:05 | 44 | [219] Salvatore Caruso v Lorenzo Giustino [255] | 3-6,5-7 | |
| Challenger Cordenons | 08/15 14:00 | 25 | [233] Lorenzo Giustino v Tommy Robredo [207] | 6-7,1-6 | |
| Challenger Prag | 07/24 09:25 | 25 | [221] Lorenzo Giustino v Enrique L.-Perez [157] | 2-6,7-6,6-7 | |
| Challenger San Benedetto | 07/21 19:00 | 28 | [247] Lorenzo Giustino v Daniel Elahi Galan [226] | 6-3,3-6,4-6 |
Lorenzo Giustino (Italian pronunciation: [loˈrɛntso dʒuˈstiːno]; born 10 September 1991, in Naples) is an Italian tennis player.
Giustino has a career-high ATP singles ranking of 127 achieved on 12 August 2019 and a career-high ATP doubles ranking of 311 achieved on 15 April 2019.
Giustino made his ATP main draw debut at the 2015 BRD Năstase Țiriac Trophy, where he qualified for the main draw.
Giustino made his Grand Slam debut at the 2020 Australian Open. He defeated Frenchman Corentin Moutet 0–6, 7–6 (7), 7–6 (3), 2–6, 18–16 in the first round of 2020 French Open as a first time main draw qualifier at this Major. The match was the second-longest in French Open history, lasting 6 hours, 5 minutes. It was his first ATP tour-level win.
He qualified for his first ATP 500 tournament at the 2021 Dubai Tennis Championships as a lucky loser receiving a bye into the second round after the withdrawal of tenth seed Borna Ćorić.
He qualified for his second ATP 500 at the 2023 Barcelona Open Banc Sabadell.