His death has been described in the Italian press as the "end of an era".
ADVERTISEMENTSilvio Berlusconi died on Monday at the San Raffaele hospital in Milan, his doctors said in a statement.
The former Italian Prime Minister was readmitted last Friday for planned medical checks related to chronic leukaemia.
The 86-year-old had recently spent 45 days in hospital being treated for the blood cancer and a lung infection, before being discharged exactly three weeks ago.
The three-time premier was one of Italy's most successful businessmen and an influential, yet controversial, politician.
He was a dominant force in Italian politics for the last 30 years and still headed his centre-right party, Forza Italia, despite suffering several health issues since 2016.
Last year, his party entered the coalition currently in government, with Berlusconi returning to parliament as an elected senator after a nine-year-long hiatus.
But many now agree Berlusconi was progressively marginalised and isolated within the context of Italian politics, losing the role of leader of the country's right-wing coalition.
Giovanni Miccichè, a former Berlusconi ally who left Forza Italia to form his own party in 2010, said on Monday Forza Italia had died with the former premier.
The Italian government announced a state funeral and proclaimed a national day of mourning on 14 June.
End of an era
Berlusconi's death is "the end of an"era" for Italy, according to the country's Repubblica newspaper.
It is the final line closing a 30-year-long chapter of Italian history that has been marked by major cultural changes, political scandals and international gaffes.
Il Cavaliere (the knight), as he was nicknamed, was born in Milan in 1936 to a middle-class family.
He began his business career in property development before founding Mediaset, Italy’s largest private broadcaster, having once sung on cruise ships as a young man.
Berlusconi rose to the top of Italian politics despite his lack of experience, pushed forward by his success as an entrepreneur.
He was elected prime minister for the first time in 1994, and then again in 2001 and 2008. In 2011, he was forced to resign following an acute debt crisis.
His career was marred by scandals - in one, nicknamed 'Ruby ter', he was accused of paying to have sex with a woman under the age of 18 - and allegations of corruption.
In late 2012 he was convicted of tax fraud, for which he served a year-long sentence doing part-time community service at a residential home in Milan.
'Rest in peace, my friend'
Berlusconi's death quickly made headlines around the world, with major newspapers summarising his life and legacy.
ADVERTISEMENTAmong the many tributes to Berlusconi, there was that of Russian President Vladimir Putin, who called him a "dear person, a true friend."
"I have always sincerely admired his wisdom, his ability to make balanced, far-sighted decisions even in the most difficult situations," Putin said in a message of condolence, adding that Berlusconi will be remembered in Russia as a "consistent and principled supporter of strengthening friendly relations between our countries."
Berlusconi was criticised for standing by Putin after the invasion of Crimea in 2014, and for recently defending the Russian president amidst the Russian war in Ukraine.
Hungary's President Viktor Orban tweeted: "Gone is the great fighter." The post was accompanied by an image of Berlusconi and Orban shaking hands which said in Italian "rest in peace, my friend."
Roberta Metsola, head of the European Parliament, tweeted: "Silvio Berlusconi: the fighter who has led the centre-right and has been the protagonist of Italian and European politics for generations. Father, entrepreneur, MEP, Prime Minister, senator. He has left his mark and will not be forgotten. Thank you, Silvio."
ADVERTISEMENTIn a video posted on Twitter, Italy's current Prime Minister Giorgia Meloni also called Berlusconi "a fighter" and "one of the most influential men in the history of the country."
Berlusconi's death frees Meloni of a sometimes troublesome ally, who has undermined several times her efforts to support Ukraine amid the Russian invasion.