The 315-foot (96-meter)-high structure - widely, though incorrectly, known as Big Ben - is one of Britain's most recognizable landmarks.
House of Commons Speaker John Bercow unveiled a new name plaque designating the structure the Elizabeth Tower.
The renaming ceremony is the culmination of a campaign by lawmakers to mark the monarch's 60 years on the throne.
The tower was completed in 1858. It houses a four-faced chiming clock and the famed 13.5 ton Big Ben bell. Over the years, people began calling the whole tower Big Ben - and likely will continue to do so.
"There's not one chance in 10,000 that visitors, that people in this country, will think of this tower as anything but Big Ben," Labour Party lawmaker Paul Flynn said.