That year, he finished sixth in league scoring, was named to the QMJHL Second All-Star Team and was awarded the Paul Dumont Trophy as the "personality of the year".
Gagné also recorded 20 goals and 13 assists for 33 points in 25 career playoff matches with the Remparts.
He has appeared in two NHL All-Star Games and has won two Bobby Clarke Trophies with the Flyers as team MVP.
The next season, Gagné posted 24 goals and 21 assists in 80 games.
He also scored a big overtime goal in Game 6 of the Eastern Conference Finals against the Tampa Bay Lightning. Once the 2004–05 NHL lockout came to an end, Gagné assumed a greater role on the Flyers and played most of the year as the left winger on the top line with Peter Forsberg and Mike Knuble.
The line became known as the "Deuces Wild" line due to their numbers (12 - Gagné, 21 - Forsberg, 22 - Knuble) and Gagné responded with his best season as a pro with 47 goals and 79 points in 72 games.
He was awarded the Bobby Clarke Trophy, which is awarded to the Flyers Team MVP.
Playing mostly on the third and fourth lines, Gagné finished with 31 points (9 goals and 22 assists) in 51 games.
The following two seasons, he would play with the Quebec Remparts, totalling 189 points (80 goals and 109 assists) in 114 games, including a 120-point season in 1998–99.
Gagné was drafted 22nd overall by the Philadelphia Flyers in the 1998 NHL Entry Draft and made the Flyers out of training camp prior to the 1999–2000 season.
His rookie season saw him play primarily at centre and score 20 goals and 28 assists in 80 games, good enough to be named to the NHL All-Rookie Team.
Playing on a line with Mark Recchi and Keith Primeau in the 2000–01 season, Gagné scored 27 goals and 32 assists in 69 games and took part in his first NHL All-Star Game.
During the All-Star Game he scored 2 goals including the game-winning goal for the North American team.
He has won silver medals at the 1999 World Junior Championships and 2005 World Championships, while winning gold at the 2002 Winter Olympics and a World Cup championship in 2004.