Johnson started his career racing in the Short-course Off-road Drivers Association (SODA), the Short-course Off-road Enthusiasts and the Mickey Thompson Entertainment Group Stadium Series (MTEG), accumulating more than 25 wins, more than 100 top-three finishes and rookie of the year honors in all three series.

From there, Johnson, a native of El Cajon, Calif., finished fourth in the 1998 ASA series standings, taking yet another rookie of the year award. In 1999, Johnson took two ASA wins and moved to third in the season standings.

Johnson also made his Busch Series debut in 1999, finishing seventh in his very first Busch Series start at the Milwaukee Mile. A year later, he finished 10th in the Busch Series standings with three sixth-place finishes.

He finally visited Victory Lane in the Busch Series in 2001, winning the inaugural Busch Series race at Chicagoland Speedway. He added four top-five and eight top-10 finishes in 2001 and finished eighth in the series points standings before making his Cup debut in 2002.

While losing the Cup rookie of the year battle to Ryan Newman in 2002, Johnson did make history by becoming the first rookie ever to lead the Cup standings on the way to a fifth-place point finish.