Walsh made his international debut at the 2009 World Youth Championships in Athletics, where he placed sixth in his shot put speciality and also competed in the qualifying of the discus throw. On 12 December 2009 Walsh recorded a put of the 5 kg shot to win the Senior Boys title at the New Zealand National Secondary School Track and Field Championships. This performance was a New Zealand Youth (Under 18) record which was broken the following day by Jacko Gill when winning the Junior Boys (Under 16) title.