Strikes in each half took Ronaldo to 105 Champions League goals as Real became the first side since AC Milan in 1990 to win back-to-back cups.
“This is one of the best moments of my career but it seems I am able to say that every year,” he said.
“People won’t be able to criticise me because the numbers don’t lie.”
Juventus were on top for large periods of an entertaining and open first 45 minutes, as Ronaldo’s opener was cancelled out by Mario Mandzukic’s superb overhead kick.
But Real were dominant after the break as goals from Casemiro, Ronaldo again and substitute Marco Asensio sealed a 12th European Cup win and a third in four seasons.
Ronaldo has now scored at least twice as many Champions League goals as any other player in the quarter-finals (20), semi-finals (13) and finals (4).
He has won the Champions League on four occasions and has now scored 11 more goals in the competition than Barcelona’s Lionel Messi – his nearest challenger.
Success capped an incredible start to management for former Real playmaker Zidane, who last month guided the club to a first La Liga title since 2012 and became the first French coach to win the Champions League twice.
“I feel like dancing,” he said. ” I consider myself a man of this house (Real Madrid).
“This club is really in my heart and we are going to enjoy this. Today is a truly historic day for Real Madrid, for all Madrid fans.”