Bedard's three-year contract was announced on the center's 18th birthday. It carries a $950,000 salary cap hit.
The player from North Vancouver, British Columbia, has been called a generational talent thanks to his offensive skills, in particular his shooting ability. Bedard was the most-hyped prospect since Connor McDavid was drafted first overall by the Edmonton Oilers in 2015.
Chicago earned the right to select Bedard after winning the NHL draft lottery, despite having only the third-best odds to earn the No. 1 pick this year at 11.5%. The Blackhawks last selected first overall in 2007, when they took winger Patrick Kane.
GM Kyle Davidson deferred on addressing any expectations at the NHL draft, saying how good Bedard is as a rookie will be up to Bedard.
"We'll let him figure that out," Davidson said. "He's a pretty special player, a very special person. We'll let him determine how special that first season is."
Bedard's signing comes as the Blackhawks cut ties with the last two players from their Stanley Cup dynasty: Kane and captain Jonathan Toews, both of whom are unrestricted free agents and not expected to return to Chicago.