The Moon River crooner lost his battle with cancer on Tuesday (25Sep12) at the age of 84 and those he has influenced, inspired and mentored have poured out their feelings on Twitter.com.
Osmond, who treated Williams like a father figure at the beginning of her pop career, has released a statement on the passing of her friend.
It reads: "The Osmonds would not exist without the foresight and generosity of our mentor, Andy Williams. Andy was the first person to affect my career. He was my very first duet and dance partner on The Andy Williams Show, where I made my debut at age 3.
"I thought he was so handsome... and always did. He gave me singing advice that I've applied to my entire career. He told me, 'Don't take singing lessons, do breathing exercises.' He would tell me to practice swimming the length of a pool underwater to increase my lung capacity. Because of Andy, I'm able to do power songs.
"No one sang more beautifully than Andy Williams. Hearing his version of Moon River never failed to move me deeply."
And she admits this Christmas (12) will be a difficult one without her mentor: "I can't imagine the holiday season without Andy Williams; we did so many specials together.
"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."