Nadal wins on injury comeback at Barcelona Open
The 22-time Grand Slam champion had not played an ATP Tour match since January but dispatched the Italian 6-2, 6-3 in one hour and 25 minutes to reach the second round.
Nadal, 37, was able to play on clay for the first time since winning the French Open in 2022 and showed flashes of his usual brilliance in a solid display.
"It was a good start -- when you return you can't get rid of the doubts in one day, above all, on a physical level," Nadal told TVE.
"Within what it could be, it was a good first round. He made mistakes and I think I played the game that I had to play."
Nadal who has triumphed at Roland Garros a record 14 times, is hoping to play there in May in what he expects to be the final year of his professional career.
The clay court king, who missed most of 2023 injured, will face Alex de Minaur on Wednesday after breezing past Cobolli.
"It will be at a speed that I don't know if I will be able to keep up with, but I'll try," Nadal said of facing the 11th-ranked De Minaur.
After a double fault to fall 30-0 behind Nadal found his rhythm, with Cobolli intimidated by the fervent support for the Spaniard on the court named after him.
Nadal converted his third break point in the fourth game for a 3-1 lead, with Cobolli surviving four more to hold at 4-2 down.
The 12-time Barcelona Open winner broke again to claim the set in 43 minutes, clenching his fist in celebration.
Cobolli handed Nadal a break for 2-0 in the second set with two more unforced errors but finally put some pressure on Nadal's serve in the third game to break back.
However Nadal broke again for 3-1 after Cobolli's third double fault and served it out to triumph.
The Spaniard did not produce any aces and his serve was effective but not explosive.
"I've gone months without being able to serve, (and) although I've got a lot of excitement to play here and do the best I can, I'm not going to go crazy with the serve," added Nadal.
"I have to serve with caution that the moment I'm in dictates... there are moments in which I feel more liberated and others in which I'm more careful."