The former NDP leader's daughter gave birth Thursday morning in Toronto to a baby girl named Solace Huxley Layton Campbell.
Sarah Layton and her husband Hugh Campbell welcomed their second daughter at Sunnybrook Hospital at 2:15 a.m. She weighs in at 9.4 pounds.
Both mom and baby are doing well, said Jack Layton's widow, NDP MP Olivia Chow.
Chow was in the room for the birth of Solace, and said she had in mind a photo of her late husband holding his granddaughter Beatrice shortly after she was born.
"To experience that baby coming out, (its) first breath, it was just magical," she said. "The cycle of life continues."
The name reminds her of the sun.
"Solace — it's comfort and warm," Chow said.
Jack Layton died Aug. 22 at the age of 61. He revealed in 2010 that he had prostate cancer, but in the month before his death Layton announced he was battling a new form of cancer. The family has not revealed what type of cancer he had, but he appeared visibly weakened at the July press conference.
Layton's death came just months after his historic election victory, in which he led his party to its best showing ever. The NDP won 37 seats in 2008, then in last year's election a surge in Quebec helped push the party to 103 seats and official Opposition status.