Vaakanainen, a 19-year-old defenseman, was selected by the Bruins with the No. 18 pick of the 2017 NHL Draft.
In 43 games with SaiPa in Liiga, Finland's top professional league, Vaakanainen (6-foot-1, 185 pounds) had 11 points (four goals, seven assists) this season. His plus-8 rating led SaiPa defenseman.
Vaakanainen had one assist in five games for Finland at the 2018 IIHF World Junior Championship.
"The plan is he'll play over here this year, which we think is a really good step for Urho," Bruins general manager Don Sweeney said. "He's played two full years in the elite league in Finland and handled himself very well, playing most nights 23 minutes. He's had lots of exposure at the World Junior level, the biggest stages. So we really think it's time for him to take the next step.
"He'll come, start in rookie camp, training camp, and see where he is. But we're excited. He's a great-skating mobile defenseman, puck-mover. Offensive blue-line play is an area where we want to continue to see him grow and get more confident to spread his wings in that area. And we're going to give him the right opportunity, so we're excited to have him."
Because Vaakanainen was drafted from a European team, he is eligible to play in the American Hockey League as a 19-year-old. Players drafted from a Canadian Hockey League team must be 20 to play in the AHL.
