The world number three had not featured since losing to Tomas Berdych in the quarter-finals of the Australian Open last month.
The Spaniard showed few signs of rust in what was his first competitive match of the year on his favoured clay court surface as he downed his Brazilian opponent in an hour and 32 minutes.
Nadal struggled with unforced errors early on, but broke Bellucci in three consecutive service games, only to cough up two breaks of his own before taking the opening set 6-4. He was more lethal early in the second set, racing to a 4-0 lead and later seeing out the set 6-1.
Second seed David Ferrer also enjoyed a straightforward opening to the tournament, defeating Daniel Gimeno-Traver of Spain 6-4, 6-3.
Two seeds did fall on the day, both from withdrawals, with fifth seed Leonardo Mayer abandoning his clash with Blaz Rola when 4-6, 7-6 (3), 4-1 down as a result of dehydration, while seventh seed Santiago Giraldo of Colombia was 6-3, 3-0 down against Juan Monaco when illness saw him bring the match to an early conclusion.