Pre-event favourite and Olympic medallist Leonardo Fabri of Italy finished fourth with a best throw of 21.35m.
Walsh entered the competition ranked eighth on his season best. His lead into the world indoor championships was a domestic affair as he competed three times on the New Zealand summer circuit.
His season’s best of 21.24m was immediately bettered by over 40cm on his opening throw.
Walsh will now set his sights on competitions in both the USA and in Europe as he builds towards the 2025 World Athletics Championships in Tokyo in September.