In may 2007 he founded the web directory Mahalo, which means "thank you" in Hawaiian. Sequoia Capital, News Corp., CBS, Mark Cuban, and Elon Musk were among the investors that contributed $20 million to the project. In 2011, the business reached a monthly peak of 15 million unique visits and turned a profit, but the Google Panda search algorithm upgrade caused a significant drop in traffic that year, and it was forced to close in 2014.
In the 1990s, Calacanis began his career as a New York-based reporter covering the internet sector. On September 24, 2003, Calacanis and Brian Alvey co-founded the blog network Weblogs, Inc. Mark Cuban made an angel investment in the company. The Weblogs, Inc. blogs company was bringing in $1,000 per day from AdSense barely two years after its launch. In October 2005, Time Warner's America Online agreed to purchase Weblogs, Inc. for $25–$30 million.
Calacanis was born to Greek and Irish parents in the Bay Ridge neighborhood of Brooklyn, New York. He has two brothers.
In 1988, he earned his high school diploma from Xaverian. After that, he went to Fordham University and graduated with a B.A. in psychology.