The 78-year-old archbishop emeritus of Montreal has suffered from several health issues related to diabetes.
He was first admitted to hospital last summer.
On its website, the Archdiocese asked for the public to give Turcotte and his family privacy during this time.
"I share this news with great sadness," wrote Christian Lépine, Montreal's Archbishop.
Turcotte was the Archbishop of Montreal for 22 years, from 1990 to 2012. He retired when he reached the maximum age limit.
He was named cardinal in 1994 by Pope John Paul II.