"He's been going downhill in the last few months, slowing up," McCallion said, calling Peterson a "very close friend."
During an illustrious career spanning seven decades, Peterson played with some of the biggest names in jazz, including Ella Fitzgerald, Count Basie and Dizzy Gillespie. He is also remembered for touring in a trio with Ray Brown on bass and Herb Ellis on guitar in the 1950s.
Peterson's impressive collection of awards include all of Canada's highest honors, such as the Order of Canada, as well as a Lifetime Grammy (1997) and a spot in the International Jazz Hall of Fame.
His growing stature was reflected in the admiration of his peers. Duke Ellington referred to him as "Maharajah of the keyboard," while Count Basie once said "Oscar Peterson plays the best ivory box I've ever heard."
"The world has lost an important jazz player," said McCallion. "It isn't just a loss for Canada, he was world famous."
Born on August 15, 1925, in a poor neighborhood southwest of Montreal, Peterson obtained a passion for music from his father. Daniel Peterson, a railway porter and self-taught musician, bestowed his love of music to his five children, offering them a means to escape from poverty.
Oscar Peterson learned to play trumpet and piano at a young age, but after a bout with tuberculosis had to concentrate on the latter.
He became a teen sensation in his native Canada, playing in dance bands and recording in the late 1930s and early 1940s. But he got his real break as a surprise guest at Carnegie Hall in 1949, after which he began touring the United States and Europe.
He quickly made a name for himself as a jazz virtuoso, often compared to piano great Art Tatum, his childhood idol, for his speed and technical skill.
He was also influenced by Nat King Cole, whose Nat King Cole Trio album he considered "a complete musical thesaurus for any aspiring Jazz pianist."
Peterson never stopped calling Canada home despite his growing international reputation. But at times he felt slighted here, where he was occasionally mistaken for a football player, standing at 6 foot 3 and more than 250 pounds.
In 2005 he became the first living person other than a reigning monarch to obtain a commemorative stamp in Canada, where he is jazz royalty, with streets, squares, concert halls and schools named after him.
Peterson suffered a stroke in 1993 that weakened his left hand, but not his passion or drive for music. Within a year he was back on tour, recording "Side By Side" with Itzhak Perlman.
As he grew older, Peterson kept playing and touring, despite worsening arthritis and difficulties walking.
"A jazz player is an instant composer," Peterson once said in a Canadian Broadcasting Corp. interview, while conceding jazz did not have the mass appeal of other musical genres. "You have to think about it, it's an intellectual form," he said