After moving to Juventus in 2005, he won a record nine consecutive Serie A titles with the club from 2012 to 2020, as well as five Coppa Italia and five Supercoppa Italiana trophies, having also played two UEFA Champions League finals in 2015 and 2017.

[7][8][9][10] He departed to the United States to join Los Angeles FC in 2022, winning the Supporters' Shield and MLS Cup in his first season, before announcing his retirement the following year at the age of 39.

In 2000, he took part in Torneo di Arco as a squad player for AC Milan's U-17 team during his tryout; while the youth coach Davide Ballardini rated his performance highly, the club could not satisfy Livorno's financial demands for a fifteen-year-old.

In his second Serie B season, Chiellini broke into the starting line-up for the club, and would go on to make 42 official appearances, also scoring four goals from his left back position.

While in the Serie B, he started playing at centre back, partnering Nicola Legrottaglie, Jean-Alain Boumsong and Robert Kovač at various stages of the season.

The surprising aspect of this is that neither were considered remotely close to pinning down a centre back position in the summer before the season, with Domenico Criscito and Jorge Andrade preferred as the starting duo.

Chiellini scored his first goal in Europe on 13 August 2008 as Juve beat Artmedia Petržalka 4–0 in the first leg of the UEFA Champions League third qualifying round tie.

Under manager Antonio Conte, Chiellini returned to his original position at left back due to Barzagli and Bonucci's good run of form.

[45] On 4 June 2015, it was confirmed that Chiellini would not participate in the 2015 UEFA Champions League Final against Barcelona as a scan on his left leg revealed he had a first degree calf muscle tear.

[50] Chiellini returned to action on 28 February to take on rivals Internazionale, yet again sustaining an injury to his thigh which caused him to limp off the pitch and substituted off in the 35th minute.

[66] On 12 September 2017, Chiellini missed the opening 2017–18 Champions League group stage match of the season against Barcelona, due to a calf injury.

[72] On 12 March, Chiellini marked his 500th appearance in a Juventus jersey with a 3–0 win home to Atlético Madrid in the Champions League round of 16 second leg to overturn a 2–0 deficit to reach the quarter-finals.

[78] On 20 October 2020, Chiellini made his 71st Champions League appearance with Juventus in the team's opening European game of the season, a 2–0 away win over Dynamo Kyiv, overtaking Alessio Tacchinardi as the club's third–most capped player of all time in the competition; however, he suffered an injury during the first half and was replaced by Merih Demiral.

[81] On 13 June 2022, Chiellini agreed to join Major League Soccer club Los Angeles FC on a contract through 2023 using Targeted Allocation Money.

[85] On 12 December 2023, three days after LAFC were defeated in the MLS Cup final by Columbus Crew, Chiellini officially announced his retirement from professional football.

[91] Chiellini was not a part of the Italian squad that won the 2006 World Cup, partially because he had transferred to Juventus in 2005 and was still working his way into consistent playing time with one of the giants of Serie A.

[97] While he also featured in the final group game, keeping a clean-sheet in a 2–0 win against France,[98] his most impressive display was arguably against Spain in the quarter-finals, where he famously neutralised the threat of the Spanish attacking duo of David Villa and Fernando Torres.

Along with Juventus teammates Andrea Barzagli and Leonardo Bonucci, and also Daniele De Rossi, he started in defence for Italy in the UEFA Euro 2012 tournament, after recovering from an injury he had encountered during the final Serie A game of the season.

As the Italian players protested to the Mexican referee Marco Antonio Rodríguez for not penalizing Suárez, Uruguay won a corner and scored, winning 1–0 to qualify for the last 16 and eliminating Italy.

On 26 June, The FIFA Disciplinary Committee announced that Suárez would be suspended for nine matches and banned from any football activity (including entering any stadium) for four months.

[121] Playing alongside Bonucci and Barzagli, Chiellini drew praise for his defensive performances, as he helped Italy keep clean-sheets in both of their opening two victories over Belgium and Sweden, which enabled the nation to top their group and advance to the second round.

[123] In the round of 16 at Stade de France in Paris on 27 June, he scored the opening goal in a 2–0 win over reigning European champions Spain and helped Italy record their third clean-sheet of the tournament.

[130] The second leg, a 0–0 home draw on 13 November, was initially thought to be his final international appearance, as Chiellini announced his retirement from the national team immediately after the match.

[139] On 17 November, he made his 100th appearance for Italy in a 0–0 draw against Portugal at the San Siro stadium in Milan, in his team's final UEFA Nations League match.

[149] Chiellini began his professional career as a defensive-minded left-back, but later made his name as an aggressive, courageous, physical, and hard-tackling centre-back, with a penchant for scoring headers from set-pieces, due to his height, aerial prowess, athleticism, and strength.

A versatile, consistent, commanding, and dependable left-footed defender, with good awareness, positional sense, and an ability to read the game, he was capable of playing both in a three or four-man defence.

"[167] Regarding Chiellini's strength and man-marking ability, his former Livorno manager Walter Mazzarri once labeled him as "a force of nature", also adding "he's a universal player that any coach would love to have on his team.

[71][157][179][189] Throughout his career with Italy and Juventus, the defensive trio of Barzagli, Bonucci, and Chiellini, which was dubbed the BBC in the media, was considered to be one of the greatest in history,[190] with pundits likening it to Italy's and Juventus's successful defensive trio of the 1930s, made up of full-backs Virginio Rosetta and Umberto Caligaris, as well as centre-half Luis Monti, who also won five consecutive league titles.

[191] With Andrea Barzagli's retirement, the subsequent Bonucci–Chiellini axis was considered, in terms of longevity and performance at high levels, one of the most solid and complementary in international football, as well as being compared to duets from the past such as Beckenbauer–Schwarzenbeck, Scirea–Gentile or Baresi–Costacurta.

[196] Shortly after his retirement, on 16 January 2024, Chiellini was appointed by his former team Los Angeles FC as a Player Development Coach in the staff of manager Steve Cherundolo.