As people were making their way into the building for the start of another work week, Philip Perea, 41, of Irving, Texas, reportedly fired a single shot into his chest at 9am local time.
Perea was rushed to the Bellevue Hospital Center but pronounced dead an hour later, police said.
Fox Television Stations CEO Jack Abernethy said in a message to employees on Monday (26 January), reported The Wall Street Journal: "This morning, a former employee at FOX 7-KTBC (Austin) committed suicide outside FOX Television Stations' headquarters in New York City.
"He was employed at our Austin television station for ten months and has not been with the station or FTS since June 2014. We are deeply saddened by this tragedy."
According to witnesses, Perea distributed fliers moments before he killed himself saying the company had "ended my career" and ruined his life.
An hour before Perea shot himself, he reportedly also sent Tweets complaining of his former employer and posted links to an eight-minute YouTube video detailing his grievances.
A suicide note and a gun were found at the crime scene on sixth avenue in Manhattan, confirmed officials.
Police are still investigating the circumstances that led to Perea's death.