McIsaac, 17, just completed his rookie season with the Halifax Mooseheads of the Quebec Major Junior Hockey League.
The six-foot-one, 190-pound defenceman is among four Mooseheads who will play at the tournament in Slovakia. Goaltender Alexis Gravel and Jocktan Chainey will also represent Canada, and Nico Hischier will play for the Swiss team.
McIsaac was the recipient of the QMJHL’s Raymond-Lagacé Trophy as Defensive Rookie of the Year.
He set a franchise record in points by a 16-year-old defenceman with 32 during the regular season.
McIsaac and his Canadian teammates open the under-18 championship Thursday against Latvia.