Ex-Argentina coach Marcelo Bielsa says a club with Leeds United's history was "impossible to turn down" after being named manager of the Championship club.
Leeds began talks with Bielsa after sacking Paul Heckingbottom on 1 June and the 62-year-old has agreed a two-year deal with an option for a third.
Bielsa has previously managed clubs in his native Argentina, Spain and France.
It will be the fifth successive season that Leeds have started a campaign with a new manager.
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"It has always been my ambition to work in England and I have had several opportunities to do so during my career, however I have always felt it was important to wait for the right project to come along and so when a club with Leeds United's history made me an offer, it was impossible to turn down," Bielsa said in a statement.
"I am excited for the challenge ahead."
Bielsa, who also had a spell in charge of Chile's national team, has been Leeds' primary target since Heckingbottom's dismissal, with managing director Angus Kinnear saying the club wanted a more experienced manager.
Bielsa will 'create a new culture'
"He is a coach that I have admired for many years and when the opportunity arose to bring him to Elland Road, we made it our top priority for the summer," said chairman Andrea Radrizzani.
"Marcelo has a wealth of experience and he will use that to create a new culture and a winning mentality at our football club.
"I would like to thank Victor Orta and Angus Kinnear for all of the hard work that has gone into this appointment and I look forward to progressing together."
The Argentine has spent time in charge of Athletic Bilbao and Marseille, and was previously at Lille.
However, he has been out of work since December after being sacked by the Ligue 1 side following a run of three wins in 13 games.
Bielsa is highly regarded by both Manchester City boss Pep Guardiola and Tottenham manager Mauricio Pochettino, with the latter calling him his "football father".
Pochettino, who worked with Bielsa during his time as head coach of the Argentina national side between 1998 and 2004, told SFR Sport: "We are a generation of coaches who were his disciples.
"How he feels football, the passion he has for football, I think we all took that from him."
'Statement of intent by Leeds'
Analysis - Adam Pope, BBC Radio Leeds
The appointment is one of the highest-profile in the near 100-year history of Leeds United. It has to rank up with the arrival of Brian Clough and Jock Stein in the 1970s.
It is a big statement of intent from Radrizzani, who, along with his management team, have gone to great lengths during a month of protracted negotiations to land Bielsa.
Bielsa may not have experience of managing in England, but he is definitely a name to capture the imagination of the United supporters.
They will hope that he has, or is given, the players to execute successfully his high-pressing, high-octane 3-3-1-3 formation over a 46-game Championship campaign.