The news has come as a shock to many in the property industry, with tributes pouring in to honour the man who built the UK's tallest building during a recession.
Nick Candy, chief executive of Candy Capital, said: "Irvine Sellar was a true visionary and the greatest example of what sheer hard work and determination can achieve. A self-made man, he pushed boundaries and challenged convention in everything he did.
"His remarkable achievements will be celebrated for generations to come, not least the Shard, which will undoubtedly become one of the defining and lasting landmarks of the London skyline. Irvine will be greatly missed by the whole industry and my sincerest condolences go out to his family for their loss."
Property industry grandee Harvey Soning, chairman of James Andrew International, said he found out about the news when Sellar's son James called early this morning.
"He said: 'I've got some very sad news about my father'," Soning said. "It took me a few minutes to absorb it."
"He was a tough, tough negotiator, but once you shook hands with him you didn't need a contract. And he was always jovial, always telling jokes."
Giles Barrie, former editor of Property Week, said: “Unlike some developers, Irvine Sellar felt a huge responsibility for how he left the London skyline. 'I’m glad it turned out all right', he once joked to me after the Shard was completed, but in truth it had been meticulously planned to the last detail.
"He created the Shard against all odds, defying planning convention and the global financial crisis, and was stimulating and challenging company to the end of his days.”
Charles Begley, executive director of the City & Westminster Property Associations, said: "Irvine Sellar was a giant in property whose boundless energy, vision and sheer determination ensured the Shard succeeded against all odds. He leaves a lasting legacy which has expanded the reach of central London into Southwark and helped transform our city."