Sophie Schnurr, 11, was killed on Dec. 21, 2018 after two half-ton trucks collided head-on on Highway 305 near Highway 11.
Police said two other people in the truck Schnurr was a passenger in were injured.
Anthony McClelland pleaded guilty in court on Tuesday to impaired driving causing death, along with impaired driving causing bodily harm.
He will be sentenced on March 19, 2020.
–With files from Thomas Piller