Canadian actor Ryan Grantham has been sentenced to life in prison after pleading guilty to murdering his mother, Barbara Waite, in 2020.

The 24-year-old, who played Jeffery Augustine in teen drama Riverdale, was sentenced at British Columbia Supreme Court in Vancouver on Wednesday.

Grantham admitted to shooting his mother in the back of the head as she played piano in their home, north of Vancouver, the court heard.

He drove roughly 200 kilometres east to the town of Hope, before turning around and driving to a Vancouver police station, where he told an officer: "I killed my mother.".

The court also heard Grantham had considered committing an act of mass violence at Vancouver's Lions Gate Bridge or at Simon Fraser University, where he had been a student, en route before turning his car around and handing himself in.

Grantham has been in custody for the past two and a half years, law enforcement officials in Vancouver told Deadline, and has been participating in a mental health program since his arrest.