The death of Butterfield, whose revelation about the listening devices and recording system set off a roaring legal battle over the president's right of executive privilege, was confirmed by his wife Kim to The Washington Post and the New York Times on Monday.
Both newspapers said he died a month shy of his 100th birthday at his home in the seaside La Jolla area of San Diego.
Butterfield once told journalist Alicia Shepard he disliked being known as the man who exposed the existence of the tapes because it made it seem as if he had "eagerly and breathlessly" told the Watergate congressional committee about them.
A native of Pensacola, Florida, who grew up in California, Butterfield attended UCLA before joining the US Air Force in 1948 and went on to serve as a combat pilot during the Vietnam War, commanding a squadron of tactical reconnaissance aircraft.
He later served as a military assistant to a high-ranking Pentagon aide, gaining White House exposure in that job.
Butterfield finally left the Air Force to join the White House staff as a deputy to Nixon's chief of staff, HR Haldeman, an old friend from UCLA.
Among Butterfield's White House duties was keeping a historical record of the presidency, which included overseeing installation of the voice-activated taping system.
Butterfield had left the White House for the top job at the Federal Aviation Administration by the time the investigation into the June 17, 1972, break-in at Democratic headquarters in the Watergate building was heating up.
He was one of the few in the White House who knew about the recording system, and upon learning that he would be questioned by the Senate Watergate Committee, known officially as the Select Committee on Presidential Campaign Activities, Butterfield resolved neither to lie nor volunteer information.
A Republican staff attorney for the committee was questioning him in a private preliminary session when he asked if the White House had a recording system. Butterfield reluctantly acknowledged there was.
On July 16, 1973, three days after his initial closed-door disclosure, Butterfield appeared before the Senate committee at a televised meeting, and Fred Thompson, then counsel for the Republicans on the committee and a future actor and senator, asked the same question.
After a long pause, Butterfield said, "I was aware of listening devices, yes, sir."
It was stunning news for the nation because it meant there was an actual record of what Nixon said, when he said it and to whom he said it.
Butterfield said the recording system had been secretly taping conversations and meetings in the Oval Office, Nixon's office in the Executive Office Building and the Cabinet room, as well as four White House telephones.
The purpose of the recordings, he said, was historical.
In a 1975 interview with People magazine, Butterfield said Nixon often forgot about the recorders and had disregarded advice to destroy the tapes because he never thought the Watergate affair would reach a point where he would have to surrender them.
"I'm sure that he hates me as much as anyone can," Butterfield said of his former boss, who died in 1994.
He said he thought Nixon should have resigned earlier.
"I don't feel awful about the president's resignation," he said.
"Not at all."
A recording made six days after the Watergate break-in proved to be Nixon's undoing - the "smoking gun" that showed he knew of the cover-up. He was heard agreeing to a plan to have the break-in investigation halted for national security reasons.
The US Supreme Court ultimately rejected White House claims of executive privilege and ordered Nixon to turn over the subpoenaed tapes as his public and political support withered. Rather than face impeachment and a Senate trial, he resigned on August 9, 1974.
Butterfield worked as an adviser to Oliver Stone on his 1995 film Nixon and had a cameo role in it as a White House staffer.
