Celtic

Mathie graduated from Celtic Boys Club to turn professional with Celtic in May 1987. He made his first-team debut in a 2–1 home defeat to Motherwell on 11 February 1989.^[3] He made eleven appearances in the Premier Division in four seasons at Celtic Park.^[3] Under the stewardship of Billy McNeill, the "Bhoys" won the league title in 1987–88, before falling behind Old Firm rivals Rangers in 1988–89, 1989–90, and 1990–91.

Morton

Mathie joined Allan McGraw's Morton in the First Division in August 1991 in a £100,000 deal. He scored 23 goals in 1991–92 and 21 goals in 1992–93, to become the club's top-scorer for two consecutive seasons. He also played in the 1992 final of the Scottish Challenge Cup at Love Street, which ended in a 3–2 defeat to Hamilton Academical. He scored a hat-trick against Clydebank on 4 August 1992, and another hat-trick in a Scottish Challenge Cup match against Forfar Athletic on 29 September.^[4] He went on to have a short loan spell with Port Vale of the English Football League's Second Division.^[1] He made three appearances in April 1993, all of them as a substitute, and did not feature as John Rudge's "Valiants" went on to win promotion out of the play-offs.^[1]

Newcastle United

In July 1993, Mathie moved from Cappielow to Kevin Keegan's Newcastle United in a deal worth £250,000.^[5] He scored a "world class" goal on his debut in a 4–2 win over Sheffield Wednesday at St James' Park on 13 September.^[6] Unable to dislodge Peter Beardsley and Andrew Cole from the starting line-up,^[6] he went on to make a further 15 Premier League appearances in 1993–94, all from the bench, and scored in wins over Coventry City and West Ham United. He started just four games in 1994–95, and scored another goal against West Ham, before he was sold on to George Burley's Ipswich Town in February 1995 for £500,000.^[5]

Ipswich Town

Mathie scored on his Ipswich debut in a 2–1 win against Southampton,^[7] one of only seven league wins that season as the "Blues" went on to be relegated out of the top-flight in 1994–95. Mathie played in the club's famous 9–0 defeat to Manchester United at Old Trafford on 4 March 1995.^[8] He scored 19 goals in 1995–96 to become the club's joint top-scorer (with Ian Marshall). His 18 First Division goals also made him the division's sixth highest scorer. This tally included a hat-trick in a 3–0 win over Sunderland at Portman Road on 2 September. He hit nine goals in 17 appearances in 1996–97, but did not feature after picking up an injury in October. Mathie scored 16 goals in 45 games in the 1997–98 season, and hit a hat-trick in a 5–0 win over rivals Norwich City on 21 February.^[9] The "Tractor Boys" reached the play-offs, but were beaten over two legs by Charlton Athletic. Mathie scored twice in the opening ten games of the 1998–99 season, before he was sold on to Paul Sturrock's Dundee United for around £700,000 in October 1998.

Dundee United

He replaced the outgoing Robbie Winters, who had moved on to Aberdeen for around the same fee (plus Billy Dodds) a few weeks previously. Mathie scored just two goals in 28 games in the 1998–99 season, and ended the season on the transfer list.^[10] He was loaned out to Preston North End for the early part of the 1999–2000 season. He scored four goals in 18 league and cup games during a three-month stay at Deepdale. Manager David Moyes went on to lead the "Lillywhites" to the Second Division title at the end of the campaign.

After returning to Dundee United, Mathie scored his first goal and only at Tannadice Park on 30 January 2000, in a 4–1 defeat of Airdrieonians in the Scottish Cup. As United's No. 9 he hit the net a total of four times in seventeen games that season, though this still left him fifth in the club's scoring charts. He played four games of the 2000–01 season; a 2–1 defeat to Celtic,^[11] 3–0 loss at Hibernian,^[12] 1–1 draw with Motherwell^[13] and 2–1 defeat by St Johnstone.^[14] He left the SPL in September 2000 after being released by new boss Alex Smith.^[15] Chairman Jim McLean later said that Mathie was "a complete disaster... a dreadful buy".^[16] Mathie in turn said that McLean's resignation "could be the best thing ever to happen to United", and that captain Jason de Vos could not be trusted, and also bemoaned the influx of foreign players at Tannadice.^[17]

Later career

Mathie joined Terry Dolan's York City on a free transfer in the English Third Division in September 2000.^[18] He scored twice in 24 appearances in 2000–01, and scored twice in 26 appearances in 2001–02. He featured ten times in 2002–03, without finding the net, and left both Bootham Crescent when his contract was cancelled in March 2003.^[5]