Nadal won three-quarters of the points on serve in a 6-1, 6-7 (5-7), 6-2 win over Monfils, whom he has beaten nine times in 11 meetings.
The 61 ATP titles for Nadal break a tie with Andrea Agassi for eighth-most all time. Guillermo Villas, who won 62 times, is seventh on the list and Bjorn Borg and Pete Sampras are tied for fifth with 64 titles.
Nadal retook the world No. 1 ranking last year when he amassed 10 titles.
He raced through the first set Saturday in 23 minutes, and Monfils converted his only break chance of the match and won one point off Nadal's serve in the tiebreaker to get to a third set.
Monfils managed four break chances in the final set but Nadal saved them all and then capped to title with his fifth break of the day.
Nadal picks up $188,600 along with the championship. He's won more than $64.8 million in his career, second only to Roger Federer's $79.2 million.
Monfils is 4-16 in title matches, having been beaten the last five times he advanced to a final. The runner-up check was worth $99,325, boosting Monfils' career winnings to more than $7 million.