Coming through the youth system at Cambridge United, Ruddy made 39 league appearances for the League Two side before a move to top-flight Everton in 2005. During his time at Goodison Park he embarked on a host of loan moves, most notably to Scottish Premier League outfit Motherwell for the 2009/10 season.
Ruddy made just one Premier League appearance for the Toffees, keeping a clean sheet against Blackburn, before moving on to Norwich City on a permanent deal in July 2010.
During his time at Carrow Road he twice won promotion to the Premier League and spent four seasons playing at the highest level with the club.He also became an England international during his time with the Canaries, winning a solitary cap against Italy in 2012.
In the summer of 2017 John moved to Wolves, and played a key role as the side won promotion to the Premier League as Championship title winners.