Wilson Clorina pleaded guilty earlier this month to the second-degree murder of Chona Manzano, who was 35, and to the first-degree murder of five-year-old Gabriel.
They were found stabbed to death at a home in May 2013.
Clorina, who is 28, sat emotionless when the sentence was read out in court.
His sentence is the longest ever handed down to a convicted murderer in Calgary.
Erwin Manzano said outside court that his son always brightened his day, and his wife put others ahead of herself.
Clorina is Manzano's first cousin, and the family had sponsored him to come to Canada and trusted him to be a nanny to their children.
In 2011, the federal government changed the Criminal Code to allow judges to impose consecutive sentences for people convicted of multiple murders.