Johnson was born in Nottingham, England, and played 13 times for the Jamaica national team, for which he qualified by descent.

Johnson scored 5 goals in 45 league appearances in the 1998–99 season and was the club's Player of the Year[4] as Birmingham finished 4th, qualifying for the play-offs.

The 1999–2000 season saw Birmingham again qualify for the play-offs and again fail to reach the final, losing in the semi-finals, this time to Barnsley, 5–2 on aggregate.

Johnson scored twice in 39 league games as Birmingham again finished 5th, losing 4–2 on penalties after a 2–2 draw in the play-off semi-final against Preston.

[6] It was a disappointing for Derby as a pre-season change of manager and the sale of several key players meant that the club finished 20th, with Johnson playing 31 games and scoring once.

Despite missing the end of the season (including all three play-off games) through injury, Johnson made 29 league appearances, scoring once.

His loan was extended for a third and final month in November 2007,[8] with Johnson playing 13 league games for Wednesday before returning to Derby at the end of December 2007.

[9] On 29 February 2008 Johnson returned to Notts County on loan for the remainder of the 2007–08 season, playing 12 times and scoring once.

He played the final league game of his career in a 3–0 defeat to Dagenham & Redbridge on 25 April 2009, announcing his retirement from professional football at the end of his contract in May 2009,[11] and remained at the club taking over the role of youth team manager from the 2009–10 season.

A succession of managers came and went over a short period of time, however Johnson was dismissed when Paul Ince was sacked and replaced by Martin Allen.

Johnson took up a coaching position with Cardiff City in July 2015, as assistant to under-21 team manager Kevin Nicholson.

[15] He was appointed as head coach of the Guyana national football team in June 2018,[16] In March 2019 he said he had previously had 10 or 11 job interviews.