| Wimbledon, London, Great Britain | 06/22 15:55 | 14 | [229] Mayer, Leonardo v Marco Trungelliti [202] | 4-6,2-6 | |
| Challenger - Nottingham | 06/15 15:00 | 25 | [229] Mayer, Leonardo v Ramkumar Ramanathan [211] | 6-3,3-6,6-7 | |
| French Open, Paris, France | 05/24 16:05 | 14 | [154] Botic Van De Zandschulp v Mayer, Leonardo [157] | 2-6,7-6,6-3 | |
| Challenger - Oeiras | 05/19 10:00 | 26 | [112] Taro Daniel v Mayer, Leonardo [158] | 6-3,6-4 | |
| Challenger - Oeiras | 05/17 11:30 | 25 | [158] Mayer, Leonardo v Londero, Juan Ignacio [95] | 4-6,6-1,6-4 | |
| Challenger Zagreb | 05/12 11:00 | 26 | [141] Nikola Milojevic v Mayer, Leonardo [159] | 7-6,6-2 | |
| Challenger Zagreb | 05/11 10:05 | 25 | [159] Mayer, Leonardo v Frederico Ferreira Silva [170] | 6-3,6-7,6-3 | |
| Challenger Biella | 05/06 15:20 | 27 | [160] Mayer, Leonardo v Alexandre Muller [202] | 3-6,4-6 | |
| Challenger Biella | 05/05 10:00 | 26 | [121] Mackenzie McDonald v Mayer, Leonardo [160] | 7-6,2-6,4-6 | |
| Challenger Biella | 05/04 13:55 | 25 | [438] Vanni, Luca v Mayer, Leonardo [160] | 6-7,0-6 | |
| ATP - Santiago | 03/08 15:30 | 25 | [110] Sousa, Pedro v Mayer, Leonardo [146] | 6-2,6-4 | |
| ATP - Buenos Aires | 02/27 20:00 | 14 | [207] Ernesto Escobedo v Mayer, Leonardo [142] | 7-5,7-6 | |
| ATP - Cordoba | 02/20 17:20 | 14 | [135] Mayer, Leonardo v Tomas Martin Etcheverry [230] | 6-7,7-6,3-6 | |
| Challenger Antalya | 02/05 11:50 | 27 | [247] Tomas Martin Etcheverry v Mayer, Leonardo [137] | 6-3,6-4 | |
| Challenger Antalya | 02/03 12:30 | 26 | [276] Akira Santillan v Mayer, Leonardo [137] | 6-7,2-6 | |
| Challenger Antalya | 02/02 09:50 | 25 | [137] Mayer, Leonardo v Lorenzo Musetti [122] | 6-4,6-3 | |
| Challenger Antalya | 01/28 13:00 | 26 | [137] Mayer, Leonardo v Cem Ilkel [219] | 5-7,1-6 | |
| Challenger Antalya | 01/28 08:00 | 25 | [137] Mayer, Leonardo v Tallon Griekspoor [155] | 6-2,6-2 | |
| French Open, Paris, France | 09/25 08:00 | 19 | [123] Mayer, Leonardo v Nikola Milojevic [143] | 7-6,2-6,3-6 | |
| French Open, Paris, France | 09/23 13:20 | 15 | [123] Mayer, Leonardo v Carlos Taberner [148] | 6-3,6-3 | |
| French Open, Paris, France | 09/22 10:00 | 14 | [123] Mayer, Leonardo v Polansky, Peter [202] | 7-5,6-0 | |
| Rome, Italy | 09/13 10:50 | 19 | [120] Mayer, Leonardo v Lorenzo Musetti [258] | 6-7,3-6 | |
| Rome, Italy | 09/12 12:05 | - | [490] Jacopo Berrettini v Mayer, Leonardo [120] | 3-6,2-6 | |
| Rome, Italy | 09/12 10:55 | 14 | Alexander Bublik v Mayer, Leonardo | Cancelled | |
| Aix En Provence, France | 09/09 09:40 | 26 | [219] Oscar Otte v Mayer, Leonardo [120] | 7-6,6-3 | |
| Aix En Provence, France | 09/07 13:20 | 25 | [120] Mayer, Leonardo v Hugo Dellien [97] | 6-3,6-2 | |
| US Open, New York, USA | 09/01 21:55 | 23 | [120] Mayer, Leonardo v Milos Raonic [18] | 3-6,2-6,3-6 | |
| Coupe Davis | 03/07 21:40 | 45 | Giraldo, Santiago v Mayer, Leonardo | Cancelled | |
| Coupe Davis | 03/06 21:00 | 45 | [148] Galan, Daniel Elahi v Mayer, Leonardo [118] | 6-1,6-4 | |
| ATP - Santiago | 02/25 16:00 | 25 | [88] Thiago Monteiro v Mayer, Leonardo [111] | 6-7,6-3,6-4 |