The Kiwi shot putter has beaten the all-time Diamond League record by four centimetres, with a throw of 22.60m in his second effort at the season-ending event in Zurich
The win sees the reigning world champion clinch the overall title and a purse of $NZ75,000, after also winning in Oslo and Morocco.
Walsh's throw was just seven centimetres shy of his personal best, set earlier this year in Auckland.
American Darrell Hill finished in second, 20cm behind Walsh. Olympic champion Ryan Crouser finished third.
"I am so happy, things went well for me. It was a tough competition today and the result is just so great," Walsh said.