World number two Nadal fought back from two sets down to defeat Daniil Medvedev in January's Australian Open final to capture his 21st Grand Slam trophy, before sealing a record-extending 14th French Open title in June for his 22nd major.
The Spaniard joins his friend and recently-retired rival Roger Federer as a five-times ITF world champion behind Pete Sampras (6) and 2021 winner Novak Djokovic (7).
"I'm very happy to be named ITF World Champion for the fifth time," the 36-year-old Nadal, who also bagged the award in 2008, 2010, 2017 and 2019, said in a statement.
