Back-to-back straight sets defeats in the Green Group by Taylor Fritz and Felix Auger-Aliassime meant the 22-time Grand slam champion missed out on the semi-finals.
But Nadal was clearly eager not to end a season that began in such spectacular fashion by succumbing to a fifth successive defeat -- something the 36-year-old had not experienced since before his career took off in 2004-05.
With world number four Ruud already assured of a semi-final berth the match was in reality a dead rubber.
See all the stats from the match
Even so the first set was full of intensity inside the Pala Alpitour where the afternoon crowd were firmly behind Nadal.
Nadal fought off a couple of break points at 4-4 in the opening set as Ruud threatened but after that the Mallorcan found the range on his forehand.
The 23-year-old Ruud went down 0-40 on serve at 5-6 and world number two Nadal needed just one chance to seal the set, punching away a volley into an empty court.
It was a similar story in the second set with nothing between the players until Nadal pounced again in the 12th game.
"I've been practising well but just not had enough matches to be at the level I need to be, not enough confidence after six tough months," Nadal said on court.
"At least I finished with a positive victory which is important."
Ruud saved one match point but Nadal then clubbed away a backhand winner to finish his season on a high.
Ruud will go on to the semi-finals but is now 0-8 against top-three opponents.
