After his suspension expired in late 2008, Harrison enjoyed a late career renaissance via a transfer of allegiance to the Dominican Republic in 2008. He made the move following discussion with his wife and his track colleague Félix Sánchez, both of whom are Dominican. He competed for his new country at the 2009 World Championships in Athletics, running in the heats of the 400 m race. He made his second world appearance soon after and helped the Dominican 4×400-meter relay team to fourth place at the 2010 IAAF World Indoor Championships. The Athletics Federation of the Dominican Republic chose Harrison as inaugural head of its high performance Olympic development program, whose first success was Luguelín Santos, silver medalist in the 2012 Olympic 400 metres at age 18. Harrison's role was recognised with an honorary master's degree in exercise science. He has also worked in high-performance programs in the NFL and NBA.