sign for Conference side Yeovil Town in July 2001 on a free transfer. Managed by his father Gary, Yeovil achieved two promotions, reaching the Football League Second Division. In this time, Johnson won the player of the year award three times consecutively. Johnson joined Scottish Premier League club Heart of Midlothian on 11 January 2006 for a transfer fee of £50,000, signing onto a two-and-a-half-year contract. His debut came as a late substitute in a 4–1 victory over Dunfermline Athletic, and he started his first game in another 4–1 win over Hearts' Edinburgh derby rivals Hibernian. Less than two months after Johnson joined Hearts, manager Graham Rix was sacked, which resulted in Johnson receiving less game time: he only made one substitute appearance prior to his departure, six months after signing. In August 2006, Johnson rejoined his father at Bristol City. On 12 August 2006, Huddersfield Town manager Peter Jackson was sent to the stands after grabbing Johnson around the throat in a touchline incident 10 minutes from full-time. He was part of the Bristol City team that won promotion to the Championship in the 2006–07 league campaign. In the 2007–08 season, Johnson enjoyed his favoured season for Bristol City, as they pushed for promotion to the Premier League, being a key figure in their run to the play-off final, which his side lost 1–0 to Hull City, narrowly missing out on promotion. On 1 January 2010, Johnson joined fellow Championship side Derby County on an initial month-long loan. He played his first game for Derby the following day, in an FA Cup fixture at Millwall, which ended in a 1–1 draw. Johnson returned to Bristol City after this spell came to an end. Despite Derby intending to retain Johnson until the end of the season, Bristol City refused. He subsequently went on loan to Chesterfield in August 2011. His stint at Bristol City concluded on 31 January 2012, after his contract was mutually terminated. On 10 February 2012, Johnson signed a two-and-half-year deal with Scottish side Kilmarnock, returning to Scotland after his departure from Hearts six years previously. On 18 March, he played in the Scottish League Cup final, in which Kilmarnock were victorious over Celtic, when Johnson set up the winning goal in their 1–0 success. He left Kilmarnock in January 2013, after his contract was mutually terminated. Johnson was eligible to play for the Gibraltar national football