Mass street partying, punctuated by fireworks, flares, horns and firecrackers, began late on Thursday after the Napoli team secured the title with a 1-1 draw away at Udinese in northeast Italy.
Naples health authorities said 203 people accessed emergency services overnight, including 22 with "red-level" critical injuries and 75 with "yellow-level" serious but not life-threatening conditions.
Health service spokesperson Anna Tagliaferri said the figure was not unusually high, with any of Naples' larger hospitals routinely handling as many as 200 emergency room cases on a "normal" day.
Wild partying had been widely expected over the "Scudetto" title win and authorities had taken several steps to try to contain risks to public order.
The city centre was pedestrianised while fireworks and firecrackers were banned, but that did not stop Neapolitans celebrating with such items throughout the night.
In an unrelated incident, one man died from gunshot wounds. Naples Prefect Claudio Palomba told RAI public radio the shooting had "nothing to do with the celebrations".
Revelries were expected to continue in the coming hours and days, with Luciano Spalletti's side set to receive a heroes' welcome upon their return from Udine later on Friday and at Sunday's home match with Fiorentina.
Prime Minister Giorgia Meloni joined the chorus of congratulations for the club, which won two previous league titles in 1987 and 1990 under the leadership of Argentine legend and local icon Diego Armando Maradona.
"33 years after the last Scudetto, Napoli are back as champions of Italy. Congratulations to the whole team, to coach Spalletti and to the entire club for all their efforts and for this well-deserved result," Meloni tweeted.
Friends and relatives of the victim of gunshot wounds, identified as a man in his 20s with a criminal record, vandalised the emergency room he had been rushed to, ANSA and other Italian news agencies said. Police are investigating the death, Palomba said.
