The 18-year-old forward spent last season with the Finnish Elite League’s Oulu Karpat, recording 28 points (13 goals, 15 assists), 22 penalty minutes and a plus-5 defensive rating in 50 games.
He also posted nine points (four goals, five assists) in 10 playoff games.
The six-foot-four, 203-pound winger has spent the past two seasons with Karpat, accumulating 39 point sand 32 penalty minutes in 71 career games.
The Tornio, Finland native represented his country most recently at the 2016 world junior hockey championship, leading the tournament in scoring with 17 points in seven games, helping Finland capture a gold medal.
His 17 points ranks him second in all-time points for a player under the age of 18 at the tournament, behind Jaromir Jagr and tying Wayne Gretzky and Eric Lindros.
Puljujarvi joins a young Oilers core led by star centre Connor McDavid.