Rutledge was raised by hand from birth at the Oaklawn Farm Zoo in Aylesford in the north-central part of the province by zoo owner Gail Rogerson, The Chronicle-Herald newspaper in Halifax reported Friday.
She told the newspaper the big cat was put down after he had stopped eating and was losing weight.
Rutledge earned a place in Guinness World Records in 1997 as the heaviest lion in captivity when he weighed 807 pounds.
Rogerson said the lifespan for captive lions averages around 14 years. Rutledge would have turned 18 in May.
The Oaklawn Farm Zoo has two other lions, one 15 and the other 17. Rogerson said Rutledge would be buried at the zoo and a memorial would be erected.
"He was a good lion," she said. "It's not easy to deal with."