Pirlo's predecessors Maurizio Sarri and Massimiliano Allegri both paid the price for the club's failure to win Europe's top football competition.
Ronaldo achieved some landmarks last term becoming the first player to score 10 or more Champions League goals for three different clubs.
Serie A: Paulo Dybala stays, Gonzalo Higuain out as Andrea Pirlo vows to bring joy back to tired Juventus
On his appointment, Pirlo said: "I think I'm in the right place at the right time. I want to bring back to Juventus some of that enthusiasm that has been lacking recently."
Champions League: Andrea Pirlo named Juventus coach after club sacks Maurizio Sarri following Round of 16 exit
Ten days ago, Pirlo had been appointed coach of Juventus’ under-23 team, which plays in Serie C. But he had not coached a game yet.
Despite leading Juve to a ninth straight Scudetto, his first as a coach, Sarri paid for the club's failure on the European stage.
It will be no exaggeration to say that Cristiano Ronaldo had more of an impact on Juventus’ record-extending ninth straight Serie A title than anyone else.
Serie A: Cristiano Ronaldo shines again as Juventus clinch ninth straight title with win over Sampdoria
It was Juventus’ first title under coach Maurizio Sarri, who brought in a completely new system.
Juventus remained six points clear of second-place Atalanta and can secure the title with a win over Sampdoria on Sunday.
Serie A: Juventus coach Maurizio Sarri plays down speculation of his exit, wants to honour his contract
Sarri has struggled to impose his own style of football, having to build a team around 35-year-old forward Cristiano Ronaldo
In their last three matches Juventus have scored seven goals, conceded nine and taken two points. They have twice squandered two-goal leads in the process.
It was Juventus' third straight match without a win after a 4-2 loss against AC Milan — after going 2-0 up — and a 2-2 draw against Atalanta.
Juventus coach Maurizio Sarri said he was surprised how much the problem had been bothering Cristiano Ronaldo.
Serie A: Cristiano Ronaldo sparkles in Gianluigi Buffon's record-breaking appearance as Juventus beat Torino
The win left Juventus with 75 points from 30 games, seven ahead of second-placed Lazio who suffered a 0-3 defeat to AC Milan
Serie A: Juventus boss Maurizio Sarri confident Miralem Pjanic will not be distracted by Barcelona move
Pjanic has suffered a dip in form this season, apparently struggling to adapt to Sarri’s style of play, and the move to Barcelona was confirmed on Monday with Brazilian Arthur Melo going the other way.
Sarri feels playing in familiar surroundings at home still makes teams comfortable and confident even without crowds.
Ronaldo had struggled since football resumed in Italy, but his return to form pushed Juventus seven points clear of second-placed Lazio, who hosts Fiorentina on Saturday.
Serie A: Lazio coach Simone Inzaghi feels loss against Atalanta will 'complicate' race towards title
As Juve extended their lead over Lazio to four points, it was hard to avoid the familiar feeling that the Turin side were about to ride off into the distance, just as they have done in previous seasons, and claim a ninth successive title.
Serie A: Cristiano Ronaldo penalty sets up Juventus win over Bologna, lifts pressure off manager Maurizio Sarri
Juventus, with 66 points from 27 games and chasing a ninth successive title, extended their lead to four points over Lazio, who visit Atalanta on Wednesday. Bologna are 10th.
Serie A: Juventus coach Maurizio Sarri denies fallout with Miralem Pjanic; confident of strong Cristiano Ronaldo comeback
Sarri has quickly found himself under pressure after Juventus were beaten on penalties by Napoli in Wednesday’s Coppa Italia final.
At 35, Juventus' Cristiano Ronaldo may have lost a step during break enforced by coronavirus pandemic
Ronaldo failed to make an impact in his first two matches back, making his run of 19 goals in 14 consecutive matches before the break seem like a distant memory.