[6] By November he had impressed sufficiently in the ten games he played in for Rosenborg for them to offer him a permanent deal, and he signed five-year contract with the club.

[7][8] In late July 2014, English Premier League club West Bromwich Albion agreed to sign Gamboa for a fee estimated in the media as around £2 million.

Because the player had insufficient recent international appearances for a work permit to be granted automatically, completion of the deal was dependent on a successful appeal to the Football Association, which was confirmed on 5 August.

[18] From January 2015 onwards to the end of the season, Gamboa only played one minute of first team football, coming on as an injury-time substitute in a fifth round FA Cup tie against West Ham in February 2015.

He then went five months without a first team appearance, before making a return to the side in February 2016 in an FA Cup fourth round replay tie against Peterborough United.

He was selected for the Costa Rica national team against part at the 2014 FIFA World Cup, and played in all five games, reaching the quarter-final where they were eventually knocked out on penalty kicks by the Netherlands.