Blazer, who was banned from all football activities for life in 2015, had been suffering from cancer.
In 2013 he pleaded guilty to bribery, money laundering and tax evasion but agreed to help investigators expose corruption in Fifa.
A larger-than-life character, he was ex-boss of Concacaf, North and Central American football’s governing body.
His information led to charges against 14 other current or former Fifa officials, and contributed to the downfall of Sepp Blatter, the organisation’s president.
Chuck Blazer: The parrot collector turned Fifa snitch
“We are truly saddened by the passing of our client and friend, Chuck Blazer,” his lawyers said in a statement.
“His misconduct, for which he accepted full responsibility, should not obscure Chuck’s positive impact on international soccer.”
The official served on Fifa’s executive committee from 1997-2013, during which time he pocketed millions to fund a globe-trotting VIP lifestyle.
A 2013 report by Concacaf’s integrity committee said he had received more than $20.6m (£16m) in commissions, fees and rental payments from the organisation between 1996 and 2011.
His personal excesses included two apartments in New York’s Trump Tower, one of which was exclusively for his cats.