In the fall of 2016, Cronin entered his last year of high school. He began looking for work after high school and could not find anything he liked. Instead, he suggested to his father, Mark X. Cronin, that they go into business together. After rejecting John's initial ideas of a "fun store" and a
food truck, John suggested they sell socks. The pair opened John's Crazy Socks on December 9, 2016. They grew the business into what has been called the World's Largest Sock Store. They are known for employing disabled people — more than half their colleagues are disabled — and for their Giving Back Program that donates money to groups like the Special Olympics, the
National Down Syndrome Society and the
Autism Society of America. Cronin became "sock buddies" with former President
George H. W. Bush Cronin has been recognized as the EY Entrepreneur of the Year and the Long Island Chapter of the Entrepreneurs Organization named him Young Entrepreneur of the Year. He was named the Millennial of the Year by the
Long Island Business News. Cronin is a frequent speaker at business events and schools and universities about business. He has delivered two
TEDx Talks. Cronin has been profiled in two documentaries: Sock Guys and Igniting Impact. == An advocate for people with disabilities ==