The audience at a school Christmas concert in British Columbia got more of a show than they bargained for when Canadian crooner Michael Bublé joined the choir on stage for a surprise performance.

Bublé attended his niece Jayde's Christmas concert at Ecole Maple Creek Middle School in Port Coquitlam on Wednesday.

With his young son Noah in his arms, the Grammy Award-winner eagerly joined in with the school's choir as they performed "Rudolph the Red-Nosed Reindeer."

Both Bublé and his sister Brandee posted video of the singalong on Instagram.

Parents and fellow classmates were thrilled over the impromptu performance, with one father in the audience calling it "wonderfully Canadian."

Meanwhile, others lamented about missing the school's concert this year.