Perhaps not among the favorites in the 2005 World Championships, Walker nonetheless won the silver medal with 5.75. Two weeks later in Rieti he set a new personal best of 5.96. In 2006 he won the World Indoor Championships in Moscow with a jump of 5.80meters. In July 2006, at Jockgrim, Germany, Brad Walker, cleared 6 meters, the best performance of the year, in a pole vault competition. He won the gold in the world championships on 1 September 2007. On 8 June 2008 Walker jumped in Eugene to a new personal and American record with 6.04. Walker qualified for the 2008 Olympics, but failed to clear a height in the preliminary rounds.