Williams' publicist said the singer died Tuesday night at his home in Branson, Mo., following a year-long battle with bladder cancer.
Williams said in November 2011 that he was diagnosed with bladder cancer but planned to continue performing at the namesake theater he built in Branson in 1992. He spent years doing two shows a night, six days a week over nine months a year.
Williams was in his 20s when he hit it big with the song, "Canadian Sunset." He had a string of hits in the 1950s and 60s, including "Can't Get Used to Losing You" and "Butterfly." He earned 18 gold and three platinum albums in his career. Williams also put his stamp on the Christmas classic, "The Most Wonderful Time of the Year."
"The Andy Williams Show," which lasted in various formats through the 1960s and into 1971, won three Emmys and featured Williams alternately performing his stable of hits and bantering casually with his guest stars.
The singer first rose to fame as part of the Williams Brothers, a singing quartet. By the time his variety show debuted in 1962, Williams was a popular solo artist. He introduced America to the Osmond Brothers and later, Donny and Marie.
Marie Osmond released the following statement following news of Williams' passing:
"I feel I've lost a dear family member and though my heart is heavy today, I feel blessed to have been graced by working and learning from such a magnificent and lasting talent and caring mentor."
Donny Osmond added:
"He truly was a great singer and I will ever be indebted to Andy for giving me the opportunity to fulfill my dreams and the opportunity to be personally inspired by such a generous talent."
At the Donny and Marie Show at the Flamingo Hotel in Las Vegas on Wednesday night, Donny Osmond paid tribute to his lifelong friend, performing the song Williams loved so much: "Moon River."
Williams is survived by his wife, Debbie, and his three children, Robert, Noelle and Christian.