With his parents having traveled from Sweden to attend his first game, Pettersson scored on his first NHL shot. The No. 5 pick in the 2017 NHL Draft kept the puck on a 2-on-1 and finished with a wrist shot just under the crossbar at 13:48 of the first period for a 1-0 lead.
"Everyone on the team congratulated me, including the coaches, and then I didn't expect a standing ovation from the crowd, so that was amazing," Pettersson said. "I'm glad to do it with all these guys, make my dream come true."
[WATCH: All Flames vs. Canucks highlights]
The 19-year-old center led the Swedish Hockey League in scoring with 56 points (24 goals, 32 assists) in 44 games and was named league MVP in the regular season and playoffs last season. He admitted to being nervous before his first NHL game but said it ended after warm ups.
"I wanted to have fun as much as possible, enjoy it," Pettersson said. "You only make one debut. And it went very good."
Video: CGY@VAN: Pettersson nets first NHL goal after prank
Having his parents in the crowd made it more special.
"Without them, I'm not here," Pettersson said.
Nikolay Goldobin, Brendan Leipsic, Jake Virtanen and Tyler Motte also scored, and Jacob Markstrom made 33 saves for the Canucks, who won their fifth straight season opener, the longest active streak in the NHL.
Playing their first game since April 2000 without either Henrik Sedin or Daniel Sedin, who retired after last season, all five Vancouver goal scorers were under 25.
"It's nice to see the young guys get rewarded," coach Travis Green said.
Pettersson made a nice lateral pass out of the slot to set up Goldobin's goal that made it 2-0 at 1:52 of the third period, and Leipsic converted a rebound at 2:20 to make it 3-0.
Video: CGY@VAN: Goldobin, Leipsic score 28 seconds apart
"It doesn't matter who scores, whether it's a young player or an older player, as long as we score goals and win games," Pettersson said.
Matthew Tkachuk and Sean Monahan scored, and Mike Smith made 18 saves for the Flames, who lost their first game with new coach Bill Peters.
Calgary finished 0-for-7 on the power play, failing on a couple attempts to get a shot on goal. Vancouver, 0-for-1 with the man advantage, scored twice shortly after killing a penalty.
"Their penalty kill did give them momentum," Peters said.
Forward James Neal, who had an assist in his Flames debut after signing as a free agent July 2, said the failed power plays cost Calgary the game.
"The power play is crucial, it wins and loses you games," Neal said. "We were getting stuck at the line, we weren't coming with enough speed and we were getting frustrated, and it was sucking energy out of us and deflating our bench."
Tkachuk made it 3-1 at 3:08 on a rebound that caught Markstrom out of position, but the Flames failed to convert a penalty to Virtanen 25 seconds later, and Virtanen scored on a breakaway for a 4-1 at 5:46, 13 seconds after his penalty expired.
Video: CGY@VAN: Tkachuk finds twine on key bounce in front
Monahan cut the lead to 4-2 at 8:08, but the Flames again failed to convert a power play on a tripping penalty at 8:48.
"Not enough pace and not enough execution on it, and not enough desperation," Peters said of the power play. "At one point, I think through 40 [minutes], we were 1-for-7 on face-offs on the power play, so it's an important part of the game."
Motte scored into an empty net with 48 seconds left to make it 5-2.
They said it
"They made some plays backdoor where we don't give our goalie a chance, and then a breakaway. When you get down and start pressing it makes for some chances but we gave up tonight, overall, I thought way too many quality chances in our zone and it's not good enough. They were the team with more energy tonight and it seemed like they were willing to do the little things better than us." -- Flames defenseman Mark Giordano
"We got a little sloppy with the puck. That was not a Picasso by any means. We've got some young guys that are learning and will learn when to place a puck behind, how to manage a puck." -- Canucks coach Travis Green after saying he liked his team's play up 1-0 a lot better than after it was 4-1
Need to know
Pettersson is the fourth player in Canucks history to have a multipoint game in his NHL debut. The others were Curt Fraser (1-1-2) and Thomas Gradin (2-1-3) on Oct. 11, 1978 against the Colorado Rockies, and Jason Jaffray (1-1-2) on Dec. 12, 2007 against the Anaheim Ducks. … Calgary defenseman Travis Hamonic missed most of the first period after a fight with Erik Gudbranson at 4:22 but returned late in the period with a full face shield and played 12:23 over the final two periods. … Canucks forward Tim Schaller, who signed as a free agent July 1, was a healthy scratch.
Flames: Host the Vancouver Canucks on Saturday (10 p.m. ET; CBC, SN360, CITY, SNW, NHL.TV)
Canucks: At the Calgary Flames on Saturday (10 p.m. ET; CBC, SN360, CITY, SNW, NHL.TV)
Video: Pettersson, big 3rd lead Canucks to win in opener