Rudi Garcia's Roma needed a win to keep the title race alive ahead of Juve's clash with Atalanta on Monday.
However, the capital club were shell-shocked by a Catania side that could have been relegated with a defeat and a Bologna win at Genoa.
A double from Mariano Izco put hosts Catania in command after 34 minutes, but Roma veteran Francesco Totti's goal eight minutes before the break restored hope for the visitors.
Attacker Gonzalo Bergessio restored Catania's two-goal advantage 11 minutes into the second half, though, and they made sure of Juve's 30th Italian top-flight championship when Pablo Barrientos added a fourth in the 79th minute.
The win is also crucial for Catania, who climbed off the bottom of the table and moved to 19th as a result. Maurizio Pellegrino's side are now just three points adrift of safety with two matches to play.
Juve's title triumph comes following a season that has seen them dominate domestically but fail to live up to expectations in European competition.
Antonio Conte's men were surprisingly eliminated from the UEFA Champions League in the group stages, and they missed the chance to reach the UEFA Europa League final on Thursday.
The final of Europe's second-tier competition will be held at Juventus Stadium but a goalless draw against Benfica earlier this week saw them lose 2-1 on aggregate.
A 3-0 win over Roma in January established an eight-point gap that Juve have shown few signs of letting slip, and the visit of Atalanta will now be little more than a celebration party for Italy's most successful club.
