The list is dominated by athletes from America's NFL, NBA and Major League Baseball competitions, although the top five athletes - Mayweather, Messi, Cristiano Ronaldo, Conor McGregor and Neymar - are from either football or combat sports.
The annual roundup of highest paid sportspeople has included at least one woman, and as many as three, since it was extended from 50 athletes to 100 in 2010, according to Forbes.
Salaries and prize money are up significantly, but endorsement earnings fell for the second straight year to $ 877 million as companies watch their sports marketing budgets.
Forbes reported that Mayweather, 41, topped sports highest-earners after banking $275 million dollars from his cross-combat super fight against mixed martial arts star Conor McGregor in August 2017.
It will come as no surprise that being talented at a sport is a good way to become a multi-millionaire, as Forbes' list of the world's 100 highest-paid athletes proves. Forbes said tennis' female stars Li Na, Maria Sharapova and Serena Williams were list regulars but Li retired in 2014 and Sharapova is still dealing with the aftermath of a 15-month suspension for using a banned substance.
This year 40 National Basketball Association players made the cut in Forbes' annual look at the world's 100 highest-paid athletes, breaking the record of 32 set last year by hoopsters.
The Forbes data reveals that the 100 highest-paid athletes earned a collective $3.8bn (£2.84bn) during the past 12 months - that's a 23% increase from the previous year.
Swiss ace Federer remains the most attractive athlete for sponsors, with endorsement deals accounting for $65 million of his earnings.
Lionel Messi and Cristiano Ronaldo complete the podium with $111M and $108M respectively.
Brazil and Paris St Germain star Neymar joins Messi and Ronaldo in the top five. As per the list, the top-100 athletes hail from a total of 22 countries and compete across 11 sporting disciplines.
Three footballers feature, along with one boxer, two basketball stars, two American Football players, a tennis icon and one UFC megastar. However, that was about $5 million less than National Basketball Association player Nicolas Batum, who landed the 100th spot on the list.