Ronaldo once again proved decisive for Juventus scoring a goal in each half to bring his league-leading tally to 14 this campaign and teeing up Federico Chiesa after the break.
Zeegelaar got a consolation for the away side to make it 3-1 in the 90th minute.
However, Paulo Dybala added the fourth deep into injury time as Andrea Pirlo's side moved on from their first defeat of the season to Fiorentina last time out.
Juve are now 5th in the league but are still 10 points off top although they have a game in hand.