| Challenger Gran Canaria | 03/01 10:00 | 25 | [299] Nikolas S Izquierdo v Lorenzo Giustino [208] | 6-2,6-2 | |
| Challenger Forli | 02/21 14:45 | 25 | [214] Lorenzo Giustino v Filip Horansky [208] | 7-6,4-6,3-6 | |
| Challenger Forli | 02/14 16:00 | 25 | [217] Lorenzo Giustino v Nuno Borges [189] | 6-7,3-6 | |
| Ausztrál 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 Napoli | 10/15 11:20 | 27 | [243] Flavio Cobolli v Lorenzo Giustino [213] | 6-4,3-6,7-5 | |
| Challenger Napoli | 10/13 12:10 | 26 | [213] Lorenzo Giustino v Andrej Martin [120] | 6-4,5-7,7-5 | |
| Challenger Napoli | 10/11 14:20 | 25 | [213] Lorenzo Giustino v Nino Serdarusic [235] | 6-4,6-1 | |
| Challenger Napoli | 10/05 12:25 | 25 | [212] Lorenzo Giustino v Riccardo Bonadio [297] | 6-3,1-6,1-6 | |
| Challenger Lisbon | 09/28 12:05 | 25 | [187] Dmitry Popko v Lorenzo Giustino [213] | Retired | |
| Challenger Bukarest | 09/25 08:00 | 28 | [204] Filip Horansky v Lorenzo Giustino [229] | 6-3,4-6,6-2 | |
| Challenger Bukarest | 09/24 08:00 | 27 | [229] Lorenzo Giustino v Riccardo Bonadio [305] | 6-2,6-3 | |
| Challenger Bukarest | 09/22 10:45 | 26 | [229] Lorenzo Giustino v Matteo Arnaldi [476] | 2-6,7-5,6-4 | |
| Challenger Bukarest | 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 Seville selejtezők | 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 | |
| Challenger Prague | 08/11 10:00 | 26 | [236] Lorenzo Giustino v Evan Furness [294] | 6-7,6-4,3-6 | |
| Challenger Prague | 08/10 08:00 | 25 | Lorenzo Giustino v Evgeny Karlovskiy | 7-6,6-2 | |
| Challenger Cordenons | 08/04 13:00 | 26 | [119] Francisco Cerundolo v Lorenzo Giustino [234] | 6-3,6-3 | |
| Challenger Cordenons | 08/02 13:50 | 25 | [234] Lorenzo Giustino v Filippo Baldi [314] | 6-7,6-4,6-2 | |
| Challenger Trieste | 07/28 17:00 | 26 | [235] Lorenzo Giustino v Timofey Skatov [308] | 6-1,2-6,1-6 | |
| Challenger Trieste | 07/26 15:00 | 25 | [215] Thomas Fabbiano v Lorenzo Giustino [235] | 3-6,4-6 | |
| Challenger Todi | 07/13 11:00 | 25 | [472] Giovanni Fonio v Lorenzo Giustino [227] | 6-4,6-3 |
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.