Lightfoot, who was suffering abdominal pain, was flown to McMaster University Medical Center in Hamilton, Ontario, early on Sunday morning from a hospital in his hometown of Orillia, Ontario.
Lightfoot, 63, was in Orillia for a concert to promote his new album, "A Painter Passing Through."
Lightfoot emerged as a prominent folk artist in the late 1960s. His hits include "If You Could Read My Mind," "Sundown" and "The Wreck of Edmund Fitzgerald," which were released in the 1970s.
His songs have been recorded by stars like Elvis Presley, Barbra Streisand, Johnny Cash, Bob Dylan, and Peter, Paul and Mary.
Lightfoot has received five Grammy nominations and has been honored in Canada with 17 Juno Awards.
In not releasing details of the entertainer's illness, Lightfoot's family is asking that his friends and fans respect their privacy.
Half a dozen concerts that had been scheduled for September have been cancelled, but a series of shows in the U.S. beginning Oct. 17 remain on the calendar.
Lightfoot's manager and longtime friend, Rick Haynes, says he believes the singer will be back on his feet in time for those performances.
"I've known Gord for 35 years and I can't remember the last time he was in a hospital," says Haynes. "He works out four days a week and he runs ten miles a week. The doctor told us that his excellent health will help in what we hope will be a speedy recovery."