| Challenger Tenerife | 01/15 10:00 | 14 | [340] Maxime Janvier v Lorenzo Giustino [282] | 3-6,4-6 | |
| Challenger Oeiras | 01/12 11:00 | 27 | [266] Joris De Loore v Lorenzo Giustino [282] | 6-2,6-4 | |
| Challenger Oeiras | 01/11 11:00 | 26 | [282] Lorenzo Giustino v Jay Clarke [241] | 6-3,7-6 | |
| Challenger Oeiras | 01/10 12:10 | 25 | [318] Elmar Ejupovic v Lorenzo Giustino [282] | 4-6,5-7 | |
| Challenger Oeiras | 01/05 11:00 | 26 | [280] Raphael Collignon v Lorenzo Giustino [281] | 6-2,7-6 | |
| Challenger Oeiras | 01/03 13:10 | 25 | [281] Lorenzo Giustino v Pol M Tiffon [293] | 6-1,3-6,6-3 | |
| Challenger Maspalomas | 12/02 10:00 | 27 | [417] Pablo Llamas Ruiz v Lorenzo Giustino [305] | 6-4,7-6 | |
| Challenger Maspalomas | 11/30 12:40 | 26 | [305] Lorenzo Giustino v Lukas Neumayer [304] | 6-3,7-5 | |
| Challenger Maspalomas | 11/29 09:30 | 25 | [305] Lorenzo Giustino v Viktor Durasovic [342] | 7-5,6-4 | |
| Challenger Ortisei | 10/25 13:30 | 25 | [167] Flavio Cobolli v Lorenzo Giustino [285] | 7-6,6-4 | |
| ATP Nápoly | 10/16 12:35 | 14 | [126] Francesco Passaro v Lorenzo Giustino [277] | 6-3,4-6,6-4 | |
| ATP Gijon | 10/09 15:05 | 19 | [277] Lorenzo Giustino v Nicolas Alvarez Varona [228] | 2-6,2-6 | |
| ATP Gijon | 10/08 16:15 | 14 | Dimitar Kuzmanov v Lorenzo Giustino | Walkover | |
| Challenger Alicante | 10/05 09:00 | 26 | [277] Lorenzo Giustino v Fabian Marozsan [185] | 2-6,6-3,1-6 | |
| Challenger Alicante | 10/04 09:00 | 25 | [352] Stuart Parker v Lorenzo Giustino [277] | 6-4,4-6,1-6 | |
| ATP Tel Aviv | 09/25 08:55 | 14 | [443] Edan Leshem v Lorenzo Giustino [246] | 6-3,6-1 | |
| Challenger Braga | 09/19 14:00 | 25 | [152] Manuel Guinard v Lorenzo Giustino [246] | 6-2,6-4 | |
| Challenger Istanbul | 09/15 10:30 | 26 | [263] Harold Mayot v Lorenzo Giustino [253] | 7-5,7-5 | |
| Challenger Istanbul | 09/13 11:05 | 25 | [253] Lorenzo Giustino v Dominik Palan [477] | 6-2,6-2 | |
| Challenger Seville selejtezők | 09/05 15:00 | 25 | [256] Lorenzo Giustino v Facundo D Acosta [249] | 6-7,6-4,1-6 | |
| Challenger Toulouse | 08/29 14:30 | 25 | [254] Frederico F Silva v Lorenzo Giustino [256] | 6-7,6-3,6-4 | |
| Challenger Banja Luka | 08/22 15:00 | 25 | Jan Choinski v Lorenzo Giustino | 6-2,7-6 | |
| Challenger San Marino | 08/11 19:55 | 26 | [253] Lorenzo Giustino v Alexander Weis [423] | 2-6,5-7 | |
| Challenger San Marino | 08/08 15:00 | 25 | [175] Nino Serdarusic v Lorenzo Giustino [253] | 6-7,6-4,3-6 | |
| Challenger Liberec | 08/02 11:35 | 25 | Lorenzo Giustino v Sumit Nagal | 3-6,6-2,6-7 | |
| Challenger Zug | 07/29 11:00 | 27 | [189] Dimitar Kuzmanov v Lorenzo Giustino [260] | 6-4,6-4 | |
| Challenger Zug | 07/27 09:00 | 26 | [260] Lorenzo Giustino v Jan-Lennard Struff [121] | 6-4,7-6 | |
| Challenger Zug | 07/26 11:55 | 25 | [260] Lorenzo Giustino v Maximilian Neuchrist [377] | 6-2,4-6,7-5 | |
| Challenger Zug | 07/25 10:00 | 19 | [260] Lorenzo Giustino v Edoardo Lavagno [395] | 6-2,6-4 | |
| Challenger Zug | 07/24 10:20 | 14 | Lorenzo Giustino v Mirko Martinez | 6-3,6-3 |
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.