Williams, who also had a home in La Quinta, California, is survived by his wife of 21 years, Debbie, and his three children with French singer Claudine Longet -- Robert, Noelle and Christian.
He was married to Longet from 1961 until their divorce in 1975. A year later, she was charged with the fatal shooting of her boyfriend, Olympic skier Spider Sabich.
Williams stood by Longet, who claimed the shooting was accidental. She spent a month in jail.
Williams' Branson theater was the first non-country venue built in the small Missouri tourist mecca.
He was born on December 3, 1927, in Wall Lake, Iowa, where he began singing with brothers Bob, Dick and Don in a Presbyterian church choir led by their parents.
Williams was just 8 when he made his professional singing debut with the Williams Brothers Quartet. The brothers were regular performers on radio station WHO's "Iowa's Barn Dance Show" in Des Moines. Their popularity grew, taking the brothers to national stations, including WLS in Chicago and WLW in Cincinnati.
Doris Day was his friend when they were both young and living in Cincinnati.
"He and his brothers sang and, of course, so did I, and often I would go over to their house and we would sing together," Day said Wednesday. "They asked me to join their group, but my vocal coach thought I should be out on my own, and so that's what I did."
Smokey Robinson said Williams "befriended me when I was just a teenager starting out in show business, and we remained friends throughout the years."
"I regret that we didn't have the chance to spend more time together," Robinson said. "He was one of the great voices and great people of our time."