2003 - In his first professional season on the tour, Leonardo Mayer collected one Futures main draw appearance and failed to qualify for two Futures events.
The Argentinian clinched his maiden Futures win in his lone Futures main draw appearance.
2004 - Mayer debuted at the Challenger level at the end of the season but didn't impress as he suffered a straight-set defeat against Victor Ionita in the Santa Cruz Challenger first round.
2005 - Mayer won his maiden Futures title at the end of the season.
2006 - Mayer earned his maiden Challenger win when he beat Norikazu Sugiyama in the Cuenca Challenger first round.
Mayer made his maiden Challenger final at the Puebla Challenger but failed to win it all as he lost to Robert Kendrick.
2007 - Mayer claimed his maiden Challenger title after beating Thomaz Bellucci in the Cuenca final.
2008 - Mayer debuted at the ATP level in Kitzbuhel, where he also clinched his first ATP win after beating Denis Gremelmayr in the first round.
2009 - Mayer debuted at the Grand Slam level after making it past the French Open qualifying. The Argentinian then earned his first Grand Slam after stunning James Blake in the first round.
Mayer also debuted at Wimbledon and the US Open as he made the second rounds at both events.
The Argentinian broke into the top-100 for the first time in his career.
2010 - Mayer debuted at the Australian Open, where he picked up a first round loss.
The Argentinian also made his Davis Cup debut against Sweden and immediately earned his maiden win in the competition after beating Joachim Johansson in the first round.
Mayer reached his maiden doubles final in San Jose, where he and Benjamin Becker ended runners-up to Mardy Fish and Sam Querrey in the final.
2011 - Mayer won his maiden ATP doubles title after he and partner Oliver Marach beat Franco Ferreiro and Andre Sa in the Buenos Aires final.
2012 - Mayer fell just short of winning his second doubles title as he and Pablo Andujar lost the Winston-Salem final against Santiago Gonzalez and Scott Lipsky.
2013 - Mayer struggled at the ATP level but won the Guayaquil Challenger title, while he also ended runner-up at the Orleans Challenger.
2014 - Mayer made his maiden ATP final in Vina del Mar but failed to win it all as he was beaten by Fabio Fognini.
However, it didn't take too long for Mayer to earn his maiden ATP title as he stunned David Ferrer in the Hamburg final to make it all the way at the tournament.
Mayer broke into the top-50 for the first time in his career and finished the season ranked inside the top-30.
2015 - Mayer fell just short of winning it all in Nice as he ended runner-up to Dominic Thiem in the final.
The Argentinian reached his career-high ranking of No. 21 in the world.
2016 - Mayer didn't have an impressive season as his best result at the ATP level were two quarter-finals and the third round at the Indian Wells Masters.
2017 - Mayer won his second ATP title on an impressive way as he entered the Hamburg main draw as a lucky loser and ended up winning it all after beating Florian Mayer in the final.
2018 - Mayer and fellow compatriot Horacio Zeballos made the Brisbane doubles final before they were beaten by Henri Kontinen and John Peers.
Mayer came close to defending his Hamburg title but fell just short as he ended runner-up in the final to Nikoloz Basilashvili.