Officials said the project to build 150,000 square feet of new space will generate thousands of construction jobs and hundreds of permanent jobs by 2015.
"This is a big day," JetBlue chief executive David Barger said at the ceremony. "We'll now have a single operation at Kennedy Airport."
Currently, JetBlue's international travelers arrive at Terminal 4, and passengers with connecting flights must transfer to Terminal 5.
The new international terminal is to open in early 2015.
Construction will include two baggage claim areas and room for a U.S. Customs and Border Protection Federal Inspection Service facility that will be able to process as many as 1,200 passengers per hour, JetBlue officials said.
The groundbreaking occurred under a walkway connecting parking lots with JetBlue's Terminal 5 -- the space where the international terminal will be built.
Officials from the airline, the Port Authority and U.S. Customs and Border Patrol stuck chrome-plated shovels into a mound of dirt for the ceremonial groundbreaking.
In May, the Port Authority's board of directors approved JetBlue's plans for a $200 million expansion at Kennedy. The authority operates Kennedy, LaGuardia and Newark Liberty airports.
Susan Baer, the Port Authority's director of aviation, said the terminal expansion will benefit international travelers for decades to come.
"It's also going to be a boost to the local economy," Baer said, adding that the authority's airports support 500,000 jobs, $22 billion in wages and $62 billion in sales.
Later this month, JetBlue will begin flying to new international destinations from Kennedy, including Cartagena, Colombia, and Grand Cayman, Barger said.