American world record holder Ryan Crouser extended his dominance in the event, throwing 22.77m in the fifth round to take gold.
Walsh hit the lead with his opening throw of 22.07m before Crouser pushed the leading mark out further to overtake the 32-year-old from Timaru.
Fellow Kiwi Maddi Wesche began the New Zealand bid in style, setting a lifetime best of 19.62m to finish fourth, within 5cm of a podium position.
The 24-year-old Aucklander extended her streak of personal bests on the global stage to offer genuine confidence she could be a medal prospect at the Paris Olympics.
In a quality competition Sarah Mitton of Canada claimed gold with a best of 20.22m to finish ahead of German Yemisi Ogunleye who set a huge PB of 20.19m in round one. The 2022 and 2023 outdoor world champion Chase Jackson snared the bronze with 19.67m, just ahead of the Kiwi in fourth.
Wesche, who was competing in her first competition since the 2023 World Championships last August, diced with danger in the early part of the competition following a first round foul with a modest 15.71m in round two. She remained in fifth until unleashing a mighty 19.62m throw in round five to add 11cm to her best set when seventh at the 2023 World Championships and move up the standings to fourth.
"I'm super happy. It was my first indoor competition, and I couldn't have asked for more than a PB. Being so close to a medal is tough but this gives me confidence going into Paris," she said.
"Nerves were definitely present for the first two throws but that's all part of the game, and I've been in this position before. Experience took over and I was pumped I could have three more throws."
Meanwhile, James Preston set a national indoor record of 1:47.59 to place fourth in heat one of the men's 800m but was eliminated from the competition.
Maia Ramsden was third in heat three of the 1500m clocking 4:06.51 to progress to the women's final, while Geordie Beamish will contest the final of the men's 1500m after finishing third in his heat in a time of 3:39.17.
