Smith was known for his aggressive mentality on the pitch and his high-pressing style of football and earned a reputation as a hard-tackling player and is noted for his high work rate.

[citation needed] In 1995, he attended the Football Association School of Excellence along with fifteen other students at Lilleshall Hall in Shropshire, where he was one of the subjects of a 1999 ITV documentary The World At Their Feet, which followed the futures of the academy's 1995 intake.

[4] That goal helped propel him into the 1998–99 English football season, as he was one-half of manager David O'Leary's first-choice striker pairing, along with Jimmy Floyd Hasselbaink.

He showed his class in 2001 while helping to lead the Leeds side through the Champions League, though his experience ended on a sour note as he was sent off in the semi-final.

Though his goal tally was not excellent by any means, his willingness to play any role on the pitch and his tireless efforts to save The Whites from relegation was greatly appreciated by the Leeds fans.

[9] The second chapter of his career began on 8 August 2004, in the Community Shield clash against Arsenal, scoring for the club with a swerving volley in the 55th minute, as United lost 3–1.

The forward scored 10 goals overall in his first season, but, with Wayne Rooney in good form and Ruud van Nistelrooy back in the team after injury, was relegated to the bench.

[12] Smith was believed to be one of several Manchester United stars who were heavily criticised by Keane, in an MUTV interview that was thought too explosive to be aired and consigned to the cutting room floor by club officials.

[13][14] It seemed that Smith's performance in the crucial home match against league leaders Chelsea would be meticulously scrutinised in the light of Keane's damning words.

[29] Smith returned to action again in the second leg of the Champions League round of 16 tie against Lille on 7 March 2007, coming on for goalscorer Henrik Larsson in the 75th minute of the 1–0 win.

[30] He made his first start at Old Trafford since his injury on 14 March in a friendly against a Europe XI to commemorate 50 years since the signing of the Treaty of Rome.

[32] He was then named in the starting line-up against Manchester City on 5 May 2007; United won the game 1–0[33] and were crowned league champions a day later, when Chelsea were held to a 1–1 draw at the Emirates Stadium against Arsenal.

His progress the following season was hampered by stress fracture of the ankle sustained in the pre-season, meaning it took until February 2009 before he played in a competitive fixture by coming on as a substitute against Everton.

With Tioté cementing his place as the in-form defensive midfielder, Smith served a lot of bench duty, although he saw a return to action in Newcastle's 3–1 cup defeat to Stevenage on 8 January 2011.

[42] After returning to full training in April 2011, it was reported by assistant manager John Carver that Smith would be in contention to start Newcastle's penultimate fixture to Chelsea with the club likely to rest Cheick Tioté to save him from a three-match ban.

On 8 June 2011, Leeds United chairman Ken Bates revealed that he was not ruling out a move to acquire Smith subject to his wage demands and fitness.

The winning goal of the game came as a result of a penalty which Smith won just before half-time, after he was fouled by Bury goalkeeper Cameron Belford before Dean Bowditch duly converted the spot-kick.

[51] On 15 May 2012 he came on as a substitute for MK Dons in the League One play-off semi-final against Huddersfield Town scoring with a diving header in injury time.

On 31 May 2012, it was reported that MK Dons manager Karl Robinson had opened talks with Smith's representatives over a permanent move to the club.

[citation needed] Smith made 18 appearances after joining the club from Newcastle United in late January, scoring two goals in the process.

[52] Smith has taken control of MK Dons XI sides in the Berks & Bucks Cup, alongside former coach Ian Wright, as well as featuring in the unfamiliar position of centre back for a game.

[58] He eventually earned his first cap in May 2001 in a friendly against Mexico, but did not make the final cut for the 2002 FIFA World Cup, and continued representing the under-21s.

[62] As of December 2020, Smith lives in the Orlando, Florida area working with male and female youngsters as a coach at the XL Soccer World Academy.