| French Open, Paris, France | 05/29 16:20 | 24 | [68] Mayer, Leonardo v Diego Schwartzman [20] | 4-6,6-3,6-4,7-5 | |
| French Open, Paris, France | 05/26 15:00 | 23 | [105] Jiri Vesely v Mayer, Leonardo [68] | 6-7,3-6,0-6 | |
| Geneva, Switzerland | 05/21 10:00 | 25 | [70] Joao Sousa v Mayer, Leonardo [68] | 6-2,6-7,6-4 | |
| ATP - Madrid | 05/04 13:30 | 45 | [98] Hugo Dellien v Mayer, Leonardo [62] | 6-2,6-4 | |
| ATP - Estoril | 05/02 17:00 | 26 | [75] Jaziri, Malek v Mayer, Leonardo [62] | 7-6,6-1 | |
| ATP - Estoril | 04/30 14:50 | 25 | [62] Mayer, Leonardo v Dusan Lajovic [23] | 7-6,6-4 | |
| ATP - Barcelone | 04/24 12:40 | 25 | [2] Rafael Nadal v Mayer, Leonardo [63] | 6-7,6-4,6-2 | |
| ATP - Barcelone | 04/22 09:00 | 24 | [80] Marius Copil v Mayer, Leonardo [63] | 3-6,7-6,5-7 | |
| ATP - Monte-Carlo | 04/13 09:00 | 45 | [61] Mayer, Leonardo v Alexei Popyrin [119] | 6-7,6-2,6-7 | |
| ATP - Miami | 03/26 00:30 | 25 | [10] Stefanos Tsitsipas v Mayer, Leonardo [62] | 6-4,6-4 | |
| ATP - Miami | 03/23 15:00 | 24 | [62] Mayer, Leonardo v Pella, Guido [32] | 6-2,6-4 | |
| ATP - Miami | 03/21 15:00 | 23 | [62] Mayer, Leonardo v Ymer, Mikael [198] | 4-6,6-3,6-4 | |
| ATP - Indian Wells | 03/09 20:35 | 24 | [19] Gaël Monfils v Mayer, Leonardo [56] | 6-4,3-6,6-3 | |
| ATP - Indian Wells | 03/08 04:55 | 23 | [59] Opelka, Reilly v Mayer, Leonardo [56] | 6-7,6-7 | |
| Sao Paulo, Brazil | 03/01 15:30 | 27 | [55] Mayer, Leonardo v Garin, Cristian [92] | 6-4,4-6,4-6 | |
| Sao Paulo, Brazil | 02/27 18:35 | 26 | [55] Mayer, Leonardo v Lorenzo Sonego [114] | 6-1,3-6,6-3 | |
| ATP - Rio De Janeiro | 02/19 16:00 | 25 | [66] Jaume Munar v Mayer, Leonardo [55] | 7-6,6-4 | |
| ATP - Buenos Aires | 02/13 19:30 | 26 | [51] Mayer, Leonardo v Pella, Guido [50] | 4-6,6-1,6-7 | |
| ATP - Buenos Aires | 02/12 17:30 | 25 | [43] Dusan Lajovic v Mayer, Leonardo [51] | 3-6,6-7 | |
| ATP - Cordoba | 02/06 00:15 | 25 | [49] Mayer, Leonardo v Delbonis, Federico [77] | 4-6,7-6,3-6 | |
| Open d'Australie | 01/17 03:00 | 24 | [13] Fabio Fognini v Mayer, Leonardo [53] | 7-6,6-3,7-6 | |
| Open d'Australie | 01/15 00:00 | 23 | [45] Nicolas Jarry v Mayer, Leonardo [53] | 6-7,6-7,6-4,3-6 | |
| ATP - Auckland | 01/09 23:00 | 27 | [54] Mayer, Leonardo v Tennys Sandgren [63] | 3-6,6-7 | |
| ATP - Auckland | 01/09 00:15 | 26 | [54] Mayer, Leonardo v Matteo Berrettini [52] | 5-7,7-6,6-3 | |
| ATP - Auckland | 01/07 23:00 | 25 | [33] Steve Johnson v Mayer, Leonardo [54] | 5-7,3-6 | |
| ATP - Auckland | 01/06 23:00 | - | Bautista-Agut, Roberto v Mayer, Leonardo | Cancelled | |
| ATP Brisbane | 12/31 07:20 | 25 | [56] Mayer, Leonardo v Miomir Kecmanovic [131] | 3-6,1-6 | |
| Basel, Switzerland | 10/23 19:30 | 25 | [54] Mayer, Leonardo v Simon, Gilles [32] | 3-6,3-6 | |
| Antwerp, Belgium | 10/15 12:40 | 25 | [53] Mayer, Leonardo v Vasek Pospisil [79] | 3-6,5-7 | |
| Shanghai, Chine | 10/09 05:00 | 24 | [53] Mayer, Leonardo v Richard Gasquet [25] | 6-1,2-6,1-6 |