Johnson played for English club Watford for 12 years, making 278 appearances and achieving back-to-back promotions to reach the Premiership in 1999.
Johnson was also to show his long-range shooting skills in the 4–0 victory over rivals Luton Town at Kenilworth Road, scoring the first goal.
The Hyde-Johnson axis continued into the 1998–99 season, with Johnson playing in Watford's drive to the play-offs and picking up a winners medal in the 2–0 final victory over Bolton Wanderers.
Johnson was to play a limited part in Watford's first Premiership season, with injuries sustained in August and January keeping him out for two months each time.
[1] Returning to Watford, Johnson featured in the final few games of the season, but still struggling for fitness and a first-team place he was released in October 2003.
Johnson moved back to Australia, joining home-town club Newcastle United Jets in the newly formed A-League.
[3] In January 2019, Johnson was appointed technical director at National League South side Wealdstone, while continuing in his role as business development manager at his former club Watford.