McKeever, 57, had been hospitalized for an embolism, The Guardian reported. He died Thursday night, the federation said.
An officer with London's Metropolitan Police for 30 years, McKeever also headed an organization that represents almost 150,000 police officers. He was chairman at a time when police officers were dealing with lost jobs and pay cuts in an era of government budget deficits.
"He led the federation through perhaps the most demanding time in history and was within two weeks of retirement," John Tully, head of the Metropolitan Police Federation, said.
McKeever also had to deal with the "Plebgate" affair. Andrew Mitchell, a Conservative member of Parliament, resigned as chief whip last year amidst allegations he called police officers "plebs" during a dispute outside No. 10 Downing Street, the prime minister's office and residence. "Plebs" is a derogatory term for plebeians or people of lower class.
McKeever had already handed over his chairmanship and planned to end his police career after 30 years on Jan. 31.
"I cannot stay within a service that is having the office of constable attacked, police officers denigrated and public safety put at risk. I will be able to fight freely outside the service; I may be retiring but I will not stop fighting for what is right and for public safety," he said.
McKeever is survived by his wife and a daughter.
Notable deaths of 2014 [PHOTOS]