The Barcelona forward earned $127 million this past year in a combination of his salary and endorsements -- $18 million more than second-place Cristiano Ronaldo, who pocketed a total of $109m.
Neymar was the third-highest on the list, having earned $105m this past year. The Brazil international took in $75m in salary, which was $10m more than Ronaldo, while Messi's income of $92m dwarfed both.
However, the Juventus forward made $44m in endorsements, which was higher than Messi's $35m and Neymar's $30m.
Messi saw his earnings increase by $16m over the past 12 months. The $111m he made in 2018 saw him finish second to Floyd Mayweather ($285m). Ronaldo ($108m) was third with Neymar ($90m) in fifth. Conor McGregor ($99m) had finished fourth.
Boxer Saul "Canelo" Alvarez was the highest-earning non-footballer on the 2019 list, with $94m in total -- just $2m of which came through endorsements, meaning he had the same salary as Messi.
Tennis player Roger Federer was the fifth highest-earner, at $93.4m. He was No. 1 in terms of endorsements, though, with $86m.
Football stars Russell Wilson ($89.5m) and Aaron Rodgers ($89.3m) were sixth and seventh, respectively, on the list, as three NBA players came in next.
LeBron James earned $89m in total with Stephen Curry having made $79.8m and Kevin Durant $65.4m.
Top-10 highest-paid athletes of 2019
1. Lionel Messi, soccer: $127m
2. Cristiano Ronaldo, soccer: $109m
3. Neymar, soccer: $105m
4. Saul "Canelo" Alvarez, boxer: $94m
5. Roger Federer, tennis: $93.4m
6. Russell Wilson, football: $89.5m
7. Aaron Rodgers, football: $89.3m
8. LeBron James, basketball: $89m
9. Stephen Curry, basketball: $79.8m
10. Kevin Durant, basketball: $65.4m