The 31-year-old top-ranked Spaniard won 6-2, 6-1 as he continued his dominance on the clay surface.
Nadal, who won his 400th match in the semifinal on Saturday against Belgium's David Goffin in straight sets (6-4, 6-0), needed just a win to consolidate to his World No. 1 ranking.
World No. 63 Tsitsipas, who was facing Nadal for the first time, did not get the better of the Spaniard, in terms of smart moves.
The 19-year-old Tsitsipas was aiming to win an inaugural ATP Tour Title since 1973 and was also the youngest ever to enter the finals of any major tennis tournament.
For Nadal, it was his 55th title on clay and 77th title overall. (ANI)