While Ronaldo rattled a late penalty against the crossbar it did little to affect the result as the Bianconeri picked up the three points they needed to clinch the Scudetto with two games to spare.
Ronaldo, who moved onto 35 goals this season, was delighted and paid tribute to Juventus' fans.
Samp, which has climbed away from the relegation zone in the last few rounds and are 15th, had Morten Thorsby sent off for second bookable offence in the 76th minute.
"It was not easy".
"It is the most attractive success, even the most hard because we wanted it and suffered", said defender Leonardo Bonucci.
"We started on a new path with a lot of scepticism around us, we gave everything, despite some slip-ups".
"Done! Champions of Italy".
The 61-year-old Italian used to be the man pursuing Juventus at the top of the table while manager of Napoli, but on Sunday night became the oldest manager ever to win the Serie A title.
"A big hug to you all".
"It's been a complicated year for everyone", he added.
Lyon won seven French titles in a row (between 2002 and 2008), while Real Madrid have won five consecutive Spanish titles twice and Huddersfield, Arsenal, Liverpool and Manchester United are the only teams to win three in a row in England.