Gibson, who attended Baldwin High School in Pittsburgh, Pennsylvania, was cut from their hockey team and still went on to make the NHL.

He was the team's primary goaltender throughout the championship, registering a .955 save percentage and a 1.36 goals against average (GAA) in seven games for the eventual gold medal winners.

[8][9] Gibson also won a bronze medal at the 2013 IIHF World Championships with Team USA's senior squad, posting a 1.56 GAA and .951 save percentage in the tournament.

[10][11] Gibson made his professional debut with the Norfolk Admirals, the American Hockey League (AHL) affiliate of the Anaheim Ducks, on April 19, 2013, playing 40 minutes in relief.

[12] On April 7, 2014, aged 20 years and 297 days, Gibson made his first NHL start for the Ducks following an injury to goaltender Frederik Andersen.

[14] Gibson made his Stanley Cup playoff debut with the Ducks in Game 4 of the Western Conference Semifinal against the Los Angeles Kings.

[16] With the departure of Jonas Hiller via free agency, the Ducks announced that both Frederik Andersen and John Gibson would compete for the number one starting job for the 2014–15 NHL season.

He did not see a single minute of play during the Ducks postseason run, missing the entire first round due to an upper-body injury.

[22] With the off-season acquisition of Anton Khudobin, rumors sparked of Gibson being traded elsewhere, which was promptly put down by Ducks general manager Bob Murray.

[30] Gibson appeared in 46 games (45 starts) going 17–19–8 before being injured in a collision with teammate Jaycob Megna during a 4–0 loss to the Ottawa Senators on February 7, 2019.

On February 13, 2019, Gibson was placed on injured reserve by the Ducks, due to head, back, and neck injuries obtained from a collision Megna.

On March 10, 2023, Gibson set a new franchise record for career saves with the team, surpassing Guy Hebert's mark of 11,813 in a 3–1 victory over the Calgary Flames.