This is a list of online tournaments in Mario Tennis Aces. The game holds monthly online tournaments, in which players need to advance through a number of matches (rounds) against other human opponents and beat the finals in order to win a championship. Depending on the degree of participation in these online tournaments, the player can earn various prizes, such as new playable characters and costumes.
The following is a list of all online tournaments hosted from the game's release up until now, along with the participation prizes handed out in each.
June 2018 - November 2018
In these months, each tournament consisted of three preliminary rounds, followed by semifinals and finals. The player could only choose to play in Standard or Simple modes, both encompassed by the Singles class. The only participation bonus in every tournament (except for the June tournament) was a new playable character, which was unlocked by simply playing at least one round in the tournament.
| Tournament date | Participation bonus |
|---|---|
| June 2018 | N/A |
| July 2018 |  Koopa Troopa |
| August 2018 |  Blooper |
| September 2018 |  Diddy Kong |
| October 2018 | File:Birdo MTA.jpg Birdo |
| November 2018 | File:Paratroopa MTA.jpg Koopa Paratroopa |
December 2018
As of December 2018, the tournaments have been reduced to only one preliminary round, followed by semifinals and finals, similarly to the COM tournaments. This tournament also added the Doubles class among the already-existent Standard and Simple classes. Exclusively in this tournament, the player could earn different participation bonuses depending on the class played.
| Tournament date | Participation bonuses | |
|---|---|---|
| December 2018 |  Petey Piranha (Standard Class or Simple Class) |
File:Shy Guy MTA.jpg Shy Guy (Doubles Class) |
January 2019 - current
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The January 2019 tournament introduced Participation Points, which are earned in accordance to the player's performance in a match. By earning enough Participation Points in a tournament, the player unlocks new alternate costumes for certain playable characters. New playable characters are still awarded by simply playing at least one match in a tournament.
| Tournament date | Participation bonuses | ||||
|---|---|---|---|---|---|
| 0 points | 300 points | 500 points | 1000 points | 2000 points | |
| January 2019 |  Luma |
N/A |  Mario overalls costume |
N/A |  Luigi overalls costume |
| February 2019 | File:MTA Boom Boom.jpg Boom Boom |
N/A | N/A | N/A |  Toad tennis apparel |
| March 2019 |  Pauline |
 Chain Chomp white and yellow cap |
N/A |  Chain Chomp white and red cap |
 Chain Chomp white and green cap |
| April 2019 |  Kamek |
 Spike blue headband and blue wristband |
N/A | Spike pink headband and pink wristband |
Spike yellow headband and yellow wristband |
| May 2019 |  Dry Bones |
TBA | TBA | TBA | TBA |
