Adams started his professional career with Aberdeen, but failed to make a first-team appearance. He moved to English side Burnley, making a couple of league appearances in the mid-1990s before returning to Scotland with Ross County in 1996.
In 2006, Adams returned to Ross County as player–coach. In November 2007, Adams was promoted to the role of player–manager, having served as caretaker manager since October. Despite the terms of Adams' appointment, his last playing appearance was in October 2007. He led Ross County to the Scottish Second Division championship in 2008, earning promotion to the First Division. Adams then led Ross County to the 2010 Scottish Cup Final, causing upset victories over SPL sides Hibernian and Celtic. County lost 3–0 to Dundee United in the Final.
Adams left Ross County on 11 November 2010 to join Hibernian as assistant manager to Colin Calderwood. Adams has had several disciplinary cases considered by the Scottish Football Association during his coaching career. At one point he was due to be banned for 18 matches, but he won an appeal against part of the suspension. Adams was then suspended for a further six matches, a sanction which Hibs have appealed against. While this appeal was ongoing, Adams described the whole disciplinary process as distressing.
Adams left Hibernian on 19 May 2011 to return to Ross County as manager. In his first season back at County, Adams guided the club to the 2011–12 Scottish First Division championship and promotion to the Scottish Premier League. County clinched the championship with five games to spare. Adams was elected PFA Scotland Manager of the Year for the 2011–12 season. At the start of 2012-13 season, Adams made seven signings, which are all free agents. After three draw and one win, Adams was named Clydesdale Bank Premier League manager of the month for August. Unfortunately, the club's 40-match unbeaten league was ended when Ross County lose 2-1 to St. Johnstone, which Adams describe the unbeaten league streak as "very proud of what they have achieved". In November 2012, Adams appointed Neale Cooper, who has just been quit by Hartlepool United, as his assistant manager. Throughout the month, Ross County was expecting to become SPL survival, but in late-December, the club began to start a winning streak, that led Ross County in the top-six and avoid relegation. In January transfer window, Adams offloaded nine players and installed six new signings. His intention was also cut the wages from the squad, to spend the fund for new signings. His winning streak continues, which resulted Adams having another Clydesdale Bank Premier League manager of the month for January. and February. During the season, Adams was subjected of being linked with Dundee United and Aberdeen. Adams was nominated PFA Scotland Manager of the Year, but lost out to Allan Johnston, which Adams missing out to win it for the second time in the row. At the end of the 2012-13 season, Adams ended his speculation by signing a new contract, which will keep him until 2016.