In the summer transfer window of 2006, Warren went on trial at Bristol Rovers, with a view to permanent contract,[3] but he eventually opted to join Team Bath.
Warren captained Team Bath to play-off promotion and played a pivotal part in the university's rise to conference football.
Team Bath folded in his last year and Warren then joined Newport County after interest from a number of clubs including Hereford.
[7] During Warren's time at Newport he was selected for Great Britain in 2009 in Serbia and in China (Shenzhen) 2011 where he finished top scorer and in 4th place and as a silver medalist.
On 12 May 2012, Warren played for Newport in the FA Trophy Final at Wembley Stadium – a match they lost 2–0 to York City.
[13] In the quarter-final of the Scottish League Cup, he scored his second goal for Inverness in a 3–0 win over Rangers, helping the club to reach the semi-final.
[14] In the first part of the season, Warren and his teammates struggled as the club found themselves near the foot of the table, but the fans soon began to see the best of him.
Alongside Josh Meekings in central defence and new goalkeeper Dean Brill, he helped Inverness keep three consecutive clean sheets in their opening matches,[19] before eventually conceding in a 2–2 draw against Celtic on 24 August 2013.
[26] Warren watched from the sidelines in the Scottish League Cup Final against Aberdeen, as Inverness lost 4–2 in the penalty shoot-out.
Alongside Josh Meekings in central defence, Warren enjoyed the club's playing style saying it made him a better player.
[31] Warren was then sent-off in the last minute of the match against Dundee United after being involved in an incident with Nadir Çiftçi, in a 1–1 draw on 24 February 2015.
On 28 June 2018, Warren's contract with Inverness was terminated by mutual consent to allow him to join League Two side Yeovil Town on a free transfer.
[39] In June 2019, after a campaign disrupted by injury Warren left Yeovil after having his contract terminated by mutual consent.