Stillie started his career as a youth player at Aberdeen and signed a professional contract in August 1995, at the age of twenty-one. In his first few months at the club, Stillie was an unused substitute as the "Dons" won the Scottish League Cup. In four years at Pittodrie, Stillie managed only twenty-six appearances and in 1999 moved to Wigan Athletic. At the Lancashire club, Stillie played 57 times, twice helping them reach the Division Two play-offs. In July 2002, Stillie moved back to Scotland to sign for Fife club Dunfermline Athletic where he was a virtual ever-present for the "Pars", making a total of 117 appearances after replacing first-choice keeper Marco Ruitenbeek in November 2002. During the 2003–04 season, Stillie was part of the "Pars" team that were runners-up to Celtic in the 2004 Scottish Cup Final. Former Dundee United manager, Gordon Chisholm signed Stillie at the start of the 2005–06 season for the "Terrors" by bringing Stillie to Tannadice for an undisclosed fee from the "Pars", after first-choice keeper Tony Bullock signed for Gillingham. Stillie was named in two Scotland squads, most recently in October 2003 but never won a cap, although he was an unused substitute in the Future Cup match versus Germany later that month. In May 2007, Stillie confirmed that he would be leaving the "Terrors" to relocate to England to pursue his English law career. Stillie helped the club to a clean sheet in the final day goalless draw at home to Motherwell. During the 2013 close season, Stillie signed a one-year contract with Gillingham, making his debut in the 4–0 away defeat to Nottingham Forest on 22 September 2007. Stillie announced his retirement at the end of the 2007–08 season to pursue his career as a lawyer. In May 2012, Stillie gained his first international cap for Sealand, playing alongside Ralf Little versus Chagos Islands, in which he conceded three goals as the match finished 3–1.
After football
After retiring as a footballer, Stillie became a lawyer. He acted in defence of the footballers David Goodwillie and David Robertson, who were accused of rape. This legal case made history as the first time a rape victim had successfully sued her attacker for civil damages. As part of the defence of Goodwillie, Stillie as his solicitor lodged court proceedings to seek to revoke legal aid support from the rape victim. In November 2019, Stillie announced that he would be contesting the general election as the Conservative candidate for the Central Ayrshire constituency. Stillie finished in second place as the incumbent MP, Philippa Whitford, was re-elected.
