Sinek began his career at the New York ad agencies Euro RSCG and Ogilvy & Mather.
He later launched his own business, Sinek Partners.

Sinek has written five books.
Start With Why, his first book, was published October 2009.
His second book, titled Leaders Eat Last, appeared on the bestseller lists of the Wall Street Journal and The New York Times.
  
As a motivational speaker, Sinek has spoken at the UN Global Compact Leaders Summit in 2016, and at TEDx conferences several times, beginning in 2009.

In March 2016, professional services firm Ernst & Young announced a program called "The Why Effect" co-developed with Sinek "to help articulate and support clients' transformation objectives".
In June 2018, The Young Turks reported a $98,000 no-bid contract from U.S. Immigration and Customs Enforcement (ICE) for "customized Simon Sinek leadership training" to take place between April 26 and May 15 2018, provided by Ernst & Young.

In November 2018, Publishers Weekly reported that Sinek would start Optimism Press, a new imprint of Penguin Random House.

Sinek is also an instructor of strategic communications at Columbia University, and is an adjunct staff member of the RAND Corporation.
Sinek began his career at the New York ad agencies Euro RSCG and Ogilvy & Mather. He later launched his own business, Sinek Partners.
Sinek has written five books. Start With Why, his first book, was published October 2009. His second book, titled Leaders Eat Last, appeared on the bestseller lists of the Wall Street Journal and The New York Times.   
As a motivational speaker, Sinek has spoken at the UN Global Compact Leaders Summit in 2016, and at TEDx conferences several times, beginning in 2009.
In March 2016, professional services firm Ernst & Young announced a program called "The Why Effect" co-developed with Sinek "to help articulate and support clients' transformation objectives". In June 2018, The Young Turks reported a $98,000 no-bid contract from U.S. Immigration and Customs Enforcement (ICE) for "customized Simon Sinek leadership training" to take place between April 26 and May 15 2018, provided by Ernst & Young.
In November 2018, Publishers Weekly reported that Sinek would start Optimism Press, a new imprint of Penguin Random House.
Sinek is also an instructor of strategic communications at Columbia University, and is an adjunct staff member of the RAND Corporation.
Simon Sinek