Fox began his career at Celtic, however he never made an appearance for the club. During his time at Celtic he was part of the side that won the double of under-19 league and Scottish Youth Cup in 2005 and 2006. On 20 August 2007, he signed for Third Division club East Fife on loan. While he was at East Fife, he won the Scottish Football League Young Player of the Month award for November 2007. On 15 January 2008, he agreed to move to Ayr United on loan for the rest of the season, however Celtic cancelled the loan and the transfer never took place.
With his contract at Celtic having expired in Summer 2009, Fox went on trial at Exeter City and Lincoln City. However, due to Celtic being entitled to a development fee and still holding his registration as he was under 23, there was no contract offer. Fox eventually took his case to FIFA although he ultimately lost and spent six months without playing.
Manager Gordon Chisholm signed Fox on 29 January 2010, for Dumfries club Queen of the South from Celtic on amateur forms. Chisholm gave Fox his debut on 16 February 2010 in place of the suspended David Hutton. Fox debuted with a clean sheet to his name in a 3–0 win for Queens at Palmerston Park against Ayr United. His next appearance came under the management of Kenny Brannigan on 3 April 2010, when he came on as a substitute in the 36th minute when Hutton injured his back away to Morton at Cappielow. The game ended in a 3–3 draw. Fox played in 6 league matches for Queen of the South. He was not on the Queens retained list at the end of the 2009–10 season.
Fox joined up for the second time with manager Gordon Chisholm at the start of July 2010 when he joined Dundee.
He was released in October when the club entered administration.
Fox was on trial for Partick Thistle during a 4–0 reserve team victory against Ayr United. He made his first team debut as a trialist on 30 October 2010, in a 1–0 victory for Partick Thistle against Cowdenbeath. At the end of the 2010–11 season, Fox received the Player of the Year award from the club.
In April 2013, Fox signed a new contract keeping him at Partick Thistle until 2015. At the end of the 2012–13 season, with Partick Thistle having won the First Division, gaining promotion to the Scottish Premier League, Fox was named in the PFA Scotland 2012–13 First Division Team of the Year.
Following a bad ankle injury in late 2013, Fox was replaced by substitute keeper and ex-Scotland international Paul Gallacher for the remainder of the 2013–14 Scottish Premiership season. Fox made an appearance on the final day of the season in a 3–2 loss to Ross County at Firhill, however he collided heavily with County's Jordan Slew and was stretchered off with ankle trauma.
On 16 August 2014, Fox was sent off against Dundee in the second game of Thistle's 2014–15 Scottish Premiership campaign following an incident with Paul McGowan. He was replaced by Paul Gallacher, who saved the subsequent Gary Harkins penalty. In November 2014, Fox called off the day before Thistle were due to play Aberdeen due to apparent food poisoning. Gallacher subsequently took his place in goals, however Thistle went on to lose the match 1–0.
Fox left the club in May 2015, having made 135 appearances in total for Thistle.
On 29 May, Fox made the switch to Scottish Premiership rivals Ross County, signing a two-year deal.
Fox was part of the Scotland under-19 squad that made it to the final of the 2006 European Under-19 Championship in Poland. He was also named in the squad that took part in the 2007 Under-20 World Cup. He played in Scotland's final match of the tournament, a 2–1 defeat against Costa Rica that saw them exit the tournament at the group stage.
Fox was selected for the full Scotland squad for the first time in November 2013, for the matches against USA and Norway.As of 23 September 2017
SPL Under-19 League: 2004–05, 2005–06
Scottish Youth Cup: 2004–05, 2005–06
Scottish First Division: 2012–13
Scottish Football League Young Player of the Month: November 2007
Scottish Football League Player of the month: January 2011
PFA Scotland First Division Team of the Year: 2012–13