He played for several clubs, including Livingston, Dundee, Celtic, Leicester City, Forfar Athletic and was a goalkeeping coach with Arbroath.
Douglas was part of the Celtic side that reached the 2003 UEFA Cup Final, under the management of Martin O'Neill.
Douglas decided that he wanted to test himself in England, rather than sit on the bench,[12] and joined Leicester City on a free transfer.
His future at the Walkers Stadium was under threat after being replaced late in the 2005–06 season by Paul Henderson and promising performances by former youth academy goalkeeper Conrad Logan.
Therefore, on 7 June 2007, Douglas was placed on the transfer list alongside Mark de Vries and Alan Maybury.
At the start of 2009–10 season, Douglas was linked a move back to England under compatriot and former teammate, Paul Lambert, now manager of Colchester United.
[39] His sending off was incorrect after referee Steven McLean judged Douglas to have swiped Chris Erskine's feet, though he claims that Lockwood shoved him to the ground.
The club appealed against his sending-off[40] and the SFA overturned the suspension, claiming the referee harshly treated Douglas.
[46] On 13 May 2013, at half-time in a match between Dundee and Kilmarnock, Douglas was given standing ovation from the fans during an emotional lap of honour.
[47] Following his departure, Douglas' feud with Brown continued when his former manager urged other club's not to sign him, claiming he was a "disrespectful liar".
[52] Douglas took over in goal for the Loons at the start of November after injury ruled usual first choice Darren Hill out for a few weeks.
Douglas played a crucial role in Forfar's promotion challenge in the 14/15 season as they made it into the championship play off final defeating Alloa 3–1 in the first leg but eventually crashing out in a 3–0 defeat in the second leg, the second goal of which Douglas gave the ball away to Liam Buchanan following a miscommunication with Darren Dods for him to strike into a near enough open net.
Following the sacking of manager Dick Campbell in December 2015, Douglas quit the Station Park side in protest.
[53] After almost a year without a club, Douglas signed for Scottish League Two side Arbroath, joining up with once again Dick Campbell who was his manager previously whilst at Forfar Athletic.
[55] Douglas subsequently re-signed for Arbroath at the end of March 2017, after on loan goalkeeper Cammy Gill was recalled by his parent club, Dunfermline Athletic.
He rejoined the Lichties soon after however, making his return to football in a victory against Queen's Park in November 2017,[57] departing the club at the end of the 2017–18 season.
Douglas was recalled to the Scotland squad in 2005 by Walter Smith for a 2006 FIFA World Cup qualifier against Italy, but he had to be substituted in the 38th minute due to injury.