Juventus clinched its fifth straight Serie A title with three matches to spare after Napoli was beaten 1-0 at Roma on Monday.
Juventus won 2-1 at Fiorentina on Sunday and Napoli needed to beat Roma to prevent the Bianconeri from clinching the title.
Radja Nainggolan scored for Roma one minute from the end on a play that began with Roma's 39-year-old captain Francesco Totti.
Juventus leads Napoli by 12 points, with Roma two points further back in a tight race for second and the last direct berth in the Champions League.
It was Juve's 32nd Italian league title -- not including the two honors that were taken away after the 2006 match-fixing scandal known as Calciopoli.
Without a match to attend, Juventus fans celebrated in Turin's central Piazza San Carlo. Juventus players celebrated in their changing room at the club's training center.
Monday is Liberation Day in Italy, a national holiday.
Later, AC Milan will visit last-place Hellas Verona and relegation-threatened Carpi will play Empoli.
Standouts Andrea Pirlo, Carlos Tevez and Arturo Vidal left Juventus after last season and the Bianconeri struggled with only one win in their opening six matches. But as the newly signed Paulo Dybala and Mario Mandzukic began to make an impact, Juventus eventually turned things around.
Dybala leads Juve with 16 goals and the team hasn't lost since October -- a run of 25 matches that includes 24 wins and one draw.
Following his two-goal performance in a 3-2 comeback win over Torino, Totti came on nine minutes from the end and lofted the ball into the area before Mohamed Salah slid it back to Nainggolan for Roma's winning strike.
Gonzalo Higuain, the Napoli forward who tops Serie A scoring this season with 30 goals, returned from a three-match ban for severe protests with the referee. It didn't take Higuain long to be involved in more controversy, this time by hitting Kostas Manolas in the left eye as he tried to hold off the Roma defender.
Higuain got away without a yellow card while Manolas had to be replaced by Ervin Zukanovic as he struggled with his vision.
Napoli forward Jose Callejon then had a goal wiped off for a debatable offside call and Roma goalkeeper Wojciech Szczesny stopped Higuain with a well-timed save.
Szczesny also denied Higuain several times in the second half and Napoli captain Marek Hamsik had an attempt into an empty net deflected by a defender in the 83rd.
Juventus last won five consecutive titles from 1931-35.
Inter Milan was the previous Italian club to win five straight titles, from 2006-10 -- its first in that streak coming when Juventus was stripped of the honor for Calciopoli.
"This is the best one because this season has really been crazy and incredible," Juventus goalkeeper and captain Gianluigi Buffon said Sunday. "It shows the technical and moral strength of the team, and the desire not to give up and continue surprising."
Last month, Buffon broke a 22-year-old Serie A record by not conceding a goal for 974 consecutive minutes. He also saved a late penalty against Fiorentina on Sunday.
Juventus faces AC Milan for the Italian Cup title on May 21, having been eliminated from the Champions League by Bayern Munich in the Round of 16.
Against Fiorentina, Juventus substitute Alvaro Morata scored the winner, seconds after Nikola Kalinic had equalized for Fiorentina late in the second half. Buffon then stopped Kalinic's spot kick in the 90th.
Mandzukic had put Juve ahead with a volley in the first half after being set up by Sami Khedira and Paul Pogba.
Juve's biggest challenge entering next season may be resisting lucrative offers for the 23-year-old Pogba, who has set up six of the team's last 14 goals to go with his eight goals this season.
Juventus can celebrate the title in front of its home fans against Carpi on Sunday.