| Challenger Tampere | 07/21 13:50 | 26 | [110] Juan Manuel Cerundolo v Lorenzo Giustino [261] | 7-6,6-1 | |
| Challenger Tampere | 07/19 16:05 | 25 | [270] Niklas-Salminen, Patrick v Lorenzo Giustino [261] | 2-6,3-6 | |
| Challenger Verona | 07/10 11:50 | 14 | Lorenzo Giustino v Remy Bertola | 2-6,3-6 | |
| Braunchsweig, Germany | 07/03 09:00 | 14 | [275] Lorenzo Giustino v Oscar Jose Gutierrez [389] | 4-6,2-6 | |
| Challenger Troyes | 06/29 10:10 | 26 | [291] Juan Bautista Torres v Lorenzo Giustino [275] | 6-4,6-3 | |
| Challenger Troyes | 06/27 17:25 | 25 | [275] Lorenzo Giustino v Olivieri, Genaro Alberto [224] | 7-5,6-7,6-1 | |
| Wimbledon, London, Great Britain | 06/20 10:00 | 14 | [273] Lorenzo Giustino v Mikhail Kukushkin [160] | 2-6,1-6 | |
| Challenger Blois | 06/13 13:25 | 25 | [263] Lorenzo Giustino v Vit Kopriva [139] | 6-2,4-6,6-7 | |
| Poznan, Poland | 05/31 08:00 | 25 | [68] Arthur Rinderknech v Lorenzo Giustino [207] | 6-4,6-0 | |
| Challenger Vicenza | 05/23 17:30 | 25 | [222] Andrea Pellegrino v Lorenzo Giustino [207] | 6-4,6-4 | |
| French Open, Paris, France | 05/18 08:00 | 15 | [287] Sousa, Pedro v Lorenzo Giustino [205] | 6-4,6-1 | |
| French Open, Paris, France | 05/16 11:40 | 14 | [205] Lorenzo Giustino v Dennis Novak [150] | 7-5,7-6 | |
| Challenger Prague | 05/08 10:20 | 29 | [176] Pedro Cachin v Lorenzo Giustino [223] | 6-3,7-6 | |
| Challenger Prague | 05/07 09:00 | 28 | [223] Lorenzo Giustino v Dimitar Kuzmanov [206] | 7-6,4-6,6-2 | |
| Challenger Prague | 05/06 09:00 | 27 | [183] Federico Gaio v Lorenzo Giustino [223] | 3-6,6-3,6-7 | |
| Challenger Prague | 05/04 10:35 | 26 | Lorenzo Giustino v Donati, Matteo | 6-1,6-3 | |
| Challenger Prague | 05/02 14:15 | 25 | [237] Marius Copil v Lorenzo Giustino [223] | 6-3,6-7,5-7 | |
| Challenger - Ostrava | 04/27 11:25 | 26 | [380] Mats Rosenkranz v Lorenzo Giustino [224] | 6-1,5-7,6-4 | |
| Challenger - Ostrava | 04/26 09:45 | 25 | [224] Lorenzo Giustino v Gregoire Barrere [228] | 6-4,5-7,6-4 | |
| Challenger Prague | 04/22 12:20 | 27 | [246] Dalibor Svrcina v Lorenzo Giustino [222] | Retired | |
| Challenger Prague | 04/21 12:15 | 26 | [222] Lorenzo Giustino v Emilio Nava [365] | 5-7,7-6,7-6 | |
| Challenger Prague | 04/20 08:30 | 25 | [222] Lorenzo Giustino v Ryan Peniston [224] | 6-2,6-3 | |
| Challenger - Barletta | 04/12 11:50 | 25 | [179] Enzo Couacaud v Lorenzo Giustino [216] | 6-4,6-4 | |
| Challenger Murcia | 04/07 12:10 | 26 | [213] Lorenzo Giustino v Ivan Gakhov [465] | 4-6,3-6 | |
| Challenger Murcia | 04/04 16:10 | 25 | [213] Lorenzo Giustino v Johan Nikles [291] | 7-6,4-6,6-4 | |
| Challenger - Oeiras | 03/29 12:30 | 25 | [256] Riccardo Bonadio v Lorenzo Giustino [208] | 6-2,6-7,6-0 | |
| Challenger - Zadar | 03/23 11:50 | 26 | [255] Duje Ajdukovic v Lorenzo Giustino [208] | 6-4,7-6 | |
| Challenger - Zadar | 03/22 10:55 | 25 | [207] Lorenzo Giustino v Zsombor Piros [240] | 6-4,5-7,7-5 | |
| Challenger Roseto | 03/14 14:15 | 25 | [169] Franco Agamenone v Lorenzo Giustino [207] | 5-7,7-5,6-4 | |
| Challenger Roseto | 03/07 13:55 | 25 | [105] Carlos Taberner v Lorenzo Giustino [207] | 6-2,6-4 |
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.