| 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 | |
| Challenger - Gran Canaria | 03/01 10:00 | 25 | [299] Nikolas S Izquierdo v Lorenzo Giustino [208] | 6-2,6-2 | |
| Challenger - Forlì | 02/21 14:45 | 25 | [214] Lorenzo Giustino v Filip Horansky [208] | 7-6,4-6,3-6 | |
| Challenger - Forlì | 02/14 16:00 | 25 | [217] Lorenzo Giustino v Nuno Borges [189] | 6-7,3-6 | |
| Australian Open | 01/10 08:10 | 14 | [205] Lorenzo Giustino v Jason Kubler [203] | 6-3,4-6,0-6 | |
| Challenger - Bendigo | 01/05 01:30 | 25 | [207] Lorenzo Giustino v Hugo Grenier [150] | 6-7,0-6 | |
| Challenger - Bendigo | 01/03 06:00 | 24 | Lorenzo Giustino v Charlie Camus | 7-6,6-3 | |
| Challenger - Bendigo | 01/03 06:00 | 24 | Lorenzo Giustino v Li Tu | Cancelled | |
| Challenger Roanne | 11/08 18:25 | 25 | [210] Lorenzo Giustino v Richard Gasquet [74] | 4-6,3-6 | |
| Challenger - Tenerife | 11/03 14:00 | 26 | [165] Fernando Verdasco v Lorenzo Giustino [211] | 6-2,6-2 | |
| Challenger - Tenerife | 11/02 12:35 | 25 | Daniel Rincon v Lorenzo Giustino | 3-6,5-7 | |
| Challenger - Napels | 10/15 11:20 | 27 | [243] Flavio Cobolli v Lorenzo Giustino [213] | 6-4,3-6,7-5 | |
| Challenger - Napels | 10/13 12:10 | 26 | [213] Lorenzo Giustino v Andrej Martin [120] | 6-4,5-7,7-5 | |
| Challenger - Napels | 10/11 14:20 | 25 | [213] Lorenzo Giustino v Nino Serdarusic [235] | 6-4,6-1 | |
| Challenger - Napels | 10/05 12:25 | 25 | [212] Lorenzo Giustino v Riccardo Bonadio [297] | 6-3,1-6,1-6 | |
| Challenger - Lissabon | 09/28 12:05 | 25 | [187] Dmitry Popko v Lorenzo Giustino [213] | Retired | |
| Challenger - Boekarest | 09/25 08:00 | 28 | [204] Filip Horansky v Lorenzo Giustino [229] | 6-3,4-6,6-2 | |
| Challenger - Boekarest | 09/24 08:00 | 27 | [229] Lorenzo Giustino v Riccardo Bonadio [305] | 6-2,6-3 | |
| Challenger - Boekarest | 09/22 10:45 | 26 | [229] Lorenzo Giustino v Matteo Arnaldi [476] | 2-6,7-5,6-4 | |
| Challenger - Boekarest | 09/20 10:00 | 25 | [185] Sumit Nagal v Lorenzo Giustino [229] | 6-3,5-7,5-7 | |
| Challenger - Istanbul | 09/14 11:40 | 25 | [80] James Duckworth v Lorenzo Giustino [229] | 7-5,6-1 | |
| Challenger - Sevilla | 09/06 17:00 | 25 | [238] Lorenzo Giustino v Flavio Cobolli [281] | 0-6,2-6 | |
| US Open | 08/25 19:40 | 14 | [237] Lorenzo Giustino v Aleksandar Kovacevic [410] | 6-3,6-7,1-6 | |
| Challenger - Verona | 08/17 13:20 | 25 | [268] Riccardo Bonadio v Lorenzo Giustino [237] | 4-6,6-4,6-4 |
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.