Arnold holds a number of A-League records: he has managed the second most games of any manager in the A-League (205), he has achieved the second most wins in the competition's history (111), he has the best career winning percentage of any A-League manager (54.2%), he has the best career unbeaten percentage of any A-League manager (81.5%), and he is one of just three managers to have won multiple A-League championships. In 2018 he replaced Bert van Marwijk as Australian coach after the 2018 FIFA World Cup.