Juventus, who won all 19 home matches on their way to a third successive league title, completed their campaign with 102 points after winning 33, drawing three and losing two of their 38 games.
They finished 17 points clear of AS Roma, who slumped to their third successive defeat when they lost 1-0 at Genoa after a late goal by Giannis Fetfatzidis.
AC Milan, who finished with a 2-1 win over Sassuolo, will miss out on European football next season after Parma took the final Europa League spot in the only outstanding issue to be settled.
Parma (58 points) clinched sixth place with a 2-0 win over relegated Livorno to finish one point ahead of Torino, who twice came from behind to draw 2-2 at fourth-placed Fiorentina, and Milan.
Rossi's penalty was his second goal in 10 days since the injury-plagued Italy striker returned from his latest knee problem which had sidelined him since January.
Club president Silvio Berlusconi has said he has not made up his mind about Seedorf's future even though the Dutchman has overseen a significant improvement in results since taking over in January.
Inter Milan, who finished fifth, completed an unhappy season by losing 2-1 at Chievo while Rafa Benitez's Napoli, in third, thrashed Verona 5-1 with two goals each from Dries Mertens and Duvan Zapata and one from Jose Callejon.
Already relegated Catania bade farewell to Serie A with a 2-1 win over Atalanta thanks to Gonzalo Bergessio's stoppage- time penalty.
Before and during the match, Juventus fans appealed to coach Antonio Conte not to leave the club.
Around 1,000 fans gathered in front of the team's hotel outside Turin before the game, holding banners asking him to stay.
Similar banners, plus a huge drawing of the feisty coach, were held aloft by supporters in the stadium during the match.
According to Italian media, Conte feels he has taken the team as far as they can go and is reported to have demanded an overhaul of the side to continue. Negotiations are due to take place early next week.
"I just want to concentrate on what we achieved this season and over three years," he said.
"I don't want anyone taking any phrases out of context and turning them into a boomerang.
Juventus went ahead after Andrea Pirlo's free kick hit the underside of the crossbar and ricocheted into the net off Cagliari goalkeeper Silvestri.
The goal was originally awarded to Pirlo by Serie A's official website, which later changed it to a Silvestri own goal.
Llorente tapped in the second from close range after Cagliari failed to clear a corner and Marchisio blasted the third after spinning past his marker with a superb piece of close control in the penalty area.
Silvestri made a brilliant save to stop a low Kwadwo Asamoah shot just before halftime before Juventus strolled through the second half.
- Sports & Recreation
- Marco Silvestri