The triumph was the club's first Scudetto since 2003, after Juve were stripped of their 2005 and 2006 titles for their involvement in the match-fixing scandal that rocked Italy six years ago.
The club was also relegated for the first time in its history as part of its punishment.
"From paradise to hell and back to paradise," Agnelli said after Sunday night's achievement.
Meanwhile, coach Antonio Conte said: "It's extraordinary and fantastic. We are delighted to have conquered an extraordinary campaign."
Juventus host Atalanta at the weekend and are one game away from completing an undefeated Serie A season.