The No. 1 pick in 2015, McDavid, who is 19 years and 266 days old, edges Colorado's Gabriel Landeskog, who was 20 days older when he received the honor in 2012. Sidney Crosby was 11 days older than that when the Pittsburgh Penguins named him permanent captain in 2007.
McDavid has played in only 45 NHL games, but he was the captain of Team North America during the World Cup, where Oilers coach Todd McLellan got an up-close look at how McDavid would handle a prominent leadership role. McDavid was also the captain in Erie, where he played junior hockey before joining the NHL.
"That [North America role] was even more of a difficult job than this,'' McDavid said Wednesday. "You're trying to get to know the guys all at the same time, while here in Edmonton everyone's so close.
"I definitely feel more comfortable in this dressing room than that one.''
Oilers coach Todd McLellan said the phenom is ready to handle the pressures that go along with the title of captain.
"He's mature beyond his years, so he's dealt with all of you since he was 14,'' McLellan said Wednesday. "He handles himself very well and takes care of his teammates in front of and with the media, which we think is very important in a Canadian franchise.''
McLellan said he sees similarities between McDavid and Crosby.
"He's an ambassador of the game,'' McLellan said of McDavid. "He understands his role.''
The Associated Press contributed to this report.