The former Juve midfielder, who made 164 appearances for the Serie A club between 2011 and 2015, earned a swift promotion after being named the club's Under-23 manager only 10 days ago.
Here, the PA news agency takes a closer look at the 41-year-old's career and the job ahead of him.
World Cup winner
Pirlo enjoyed a trophy-laden career with club and country. He won Serie A six times and lifted the Champions League twice across successful spells with AC Milan and Juve. His 116 international caps place him fifth in the all-time list of appearances for Italy. Undoubtedly the pinnacle of his career came in 2006 when he lifted the World Cup after converting the opening penalty in the shoot-out win over France in Berlin. He retired in 2017 following a spell with Major League Soccer side New York City.
Impose his identity
Pirlo was renowned as a silky playmaker with a superb range of passing, excellent close control, and a specialism for set-pieces. His accomplished, possession-based performances made him one of the celebrated central midfielders of his generation. Given his lack of managerial experience, little is currently known of Pirlo's tactical preferences. Managing a major club like Juve is ultimately all about winning but, after Sarri's methods failed to impress in Turin, harnessing the slickness which defined his career to create an easy-on-the-eye style of play would certainly help satisfy demanding fans.
Become genuine Champions League contenders
Winning Serie A has become almost routine for Juve which in turn has served to highlight their repeated European failures. It is now 24 years since the club tasted Champions League glory, a season before Pirlo won Serie B with Brescia in the early stages of his illustrious career. Juve have been runners-up five times since, including in 2003 to a Milan team containing Pirlo. Sarri paid with his job after Friday's last-16 loss to Lyon and turning domestic dominance into European success is perhaps the top task facing Pirlo.
Play to Ronaldo's strengths
Cristiano Ronaldo may be 35 but he remains prolific and has two years remaining on his contract. The Portugal international, who scored a remarkable 37 club goals over the course of the prolonged 2019-20 campaign, admitted the club "must live up to the highest expectations" and "must always think like the best in the world" in the aftermath of the Lyon loss. Ronaldo clearly remains hungry for success and Pirlo must rejuvenate his squad without adversely affecting his star man.
Prepare a long-term plan
While Pirlo must hit the ground running as Juve seek a 10th successive Serie A title, he will surely have one eye on the future in terms of personnel. The squad he inherits is packed with quality. However, plenty of those players are aged 30-plus. As mentioned, Ronaldo currently shows no sign of slowing down, but Pirlo's former team-mates Gianluigi Buffon, Giorgio Chiellini and Leonardo Bonucci cannot go on forever, while Sami Khedira, Blaise Matuidi, Juan Cuadrado and Gonzalo Higuain also fall into the 'veteran' category. Playmaker Miralem Pjanic already leaves a gap having agreed a move to Barcelona.