He has played for Leicester Tigers since 1989. Although in 1989, Johnson was approached by former All Black Colin Meads to try out for King Country side in New Zealand. Johnson's try out was successful and he played two seasons for King Country. In 1990, he was selected for the New Zealand under 21 side which went on a tour of Australia. However, in late 1990 he returned to England.
Under his captaincy (1997 to 2003) the Leicester Tigers won four Zurich Premiership titles and two Heineken Cups.
He made his England debut in 1993, taking over the captaincy in 1999. He lead the side to three Six Nations titles and to its success in the 2003 World Cup. He retired from international rugby in January 2004.
He is only player to have captained the Lions on two tours. Against South Africa in 1997 his side won the series 2-1 but lost against Australia 1-2 in 2001.