Career
Chiellini joined the youth teams at Livorno at age six and started out as a central midfielder. As he matured, he switched to playing as a winger and finally he found his position as a left back. He played in the clubs' youth academy between 1990 and 2000, before earning first team call-ups for the 2000–01 Serie C1 season. In his first season with the first team, Chiellini made three appearances and followed that up with five more appearances the following season. In the summer of 2002, he was signed by Juventus in co-ownership deal, for €3.1 million, (who also saw Marco Amelia, moved to opposite direction, for €2.8 million) however, he was loaned back to Livorno for the 2002–03 Serie B season, after Livorno had earned promotion. In his first Serie B season, Chiellini made six seasonal appearances, also making his Coppa Italia debut. 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. In June 2004, Livorno officially bought back Chiellini for €3 million. During his four-season spell with the clubs' first team, Chiellini made 57 total appearances, scoring four goals, before his high-profile transfer to European giants and scudetto holders Juventus.
Fiorentina
Chiellini was signed by Juventus in the summer 2004 for €6.5 million, but was immediately sold in a co-ownership deal to Fiorentina for €3.5 million, where he played during the 2004–05 Serie A season. In his lone season with the Tuscan club, Chiellini was a regular in the club's starting XI, making 42 official appearances, also scoring three goals.
Juventus
After an excellent first season in Serie A, Chiellini was recalled for the 2005–06 season and Juventus paid €4.3 million for the rest of his contract. He became a regular under Fabio Capello and made 23 appearances in his first season with the club, also helping the club to their 29th scudetto (which was later revoked due to the Calciopoli scandal). Following Juventus' enforced relegation due to the Calciopoli scandals, Chiellini decided to remain in Turin despite the high-profile transfers of Zlatan Ibrahimović, Patrick Vieira, Emerson, Gianluca Zambrotta, and Fabio Cannavaro.
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. Juventus won promotion with the best goal difference, conceding only 30 goals and scoring over 80. He scored a rare double in a 5–1 thrashing away at Arezzo in May, a result that sealed promotion for the bianconeri mathematically.
With Juventus back in Serie A, Chiellini again was a starter for the club at left back, but following injuries to Jorge Andrade and Domenico Criscito, he was shifted to centre back again. Chiellini had a tremendous season and eventually made the position his own. Alongside fellow centre-half Nicola Legrottaglie, the duo were instrumental as Juventus finished the season with the joint second-best defensive record. The surprising aspect of this is that neither were considered remotely close to pinning down a center-back position in the summer before the season, with Domenico Criscito and Jorge Andrade preferred as the starting duo. He has been a regular fixture in the Bianconeri backline since their return to Serie A and was notably named Man of the Match in a game against Juventus' bitter rivals Internazionale when he won a physical and heated duel with former teammate Zlatan Ibrahimović, keeping the Swedish striker at bay. Chiellini extended his original contract from until 2009 to 2011 on 12 October 2006. On 27 April 2008, Chiellini scored twice for Juventus in 5–2 win over Lazio that confirmed the bianconeri's place in the Serie A top four. On 26 June 2008, Chiellini extended his contract with Juventus until 2013.
During the 2008–09 season, Chiellini remained as first choice in central defense alongside Nicola Legrottaglie. 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. Four days later, he injured his left knee again during the Trofeo Luigi Berlusconi against Milan and missed the start of the Serie A season, returning to duty in September starting in each of Juve's first three Champions League group games. At the end of the year, he was named Serie A Defender of the Year for 2008 at the annual Oscar del Calcio awards ceremony. On 10 March 2009, Chiellini was sent off for a second bookable offense during the Champions League first knockout round second leg tie at home in a tightly-contested match against Chelsea ,but Juventus were eliminated 3–2 on aggregate after holding the former English champions to a 2–2 draw.
An injury sustained in the win over Fiorentina on 6 March 2010 sidelined him for several important games and, in his absence, Juventus embarked on a miserable run of form, conceding nine goals in the four games he missed. He marked his return by scoring the opening goal away at Napoli but was unable to prevent Juventus from succumbing to a 3–1 defeat.] On 23 November 2010, Chiellini extended his contract with again until 30 June 2015 and was deservedly given a pay raise.
During the beginning of the 2010–11 season, Chiellini was mostly partnered with newly-signed youngster Leonardo Bonucci. With the arrival of fellow Italy international Andrea Barzagli in the winter transfer window, Chiellini occasionally played at left back to accommodate the Bonucci-Barzagli partnership and sometimes partnered Barzagli. Under manaer Antonio Conte, he returned to his original position at left back due to Barzagli and Bonucci's good run of form. After struggling to re-adapt back to his former position, he grew into his role and managed to keep Paolo De Ceglie, the only other natural left back in the squad, on the bench for much of the first half of the 2011–12 season.