''I came here to win but I knew that I would have to throw well to beat these guys,'' Walsh said.
''It was a crazy competition but I finished with a boom. I came here to retain my title and it is a good feeling to achieve that.''
Seven athletes were over 21.00m in the contest, the most ever for an indoor shot put competition.
Walsh's throw, just two days after his 26th birthday, added 0.10m to his national and Oceania record and was 0.07m further than the previous championship record of 22.24m, set by East German Ulf Timmermann in 1987.
''The crowd was awesome, the last 20 minutes was awesome with the crowd so close and they pushed me to throw far,'' Walsh said.
Top Americans Ryan Crouser, the Rio Olympic champion, and Joe Kovacs were missing from the meet having failed to contest the Amereican championships, while next best Ryan Whiting had an off day.
But Crouser and Kovacs, silver medallist in Rio, would have struggled to topple the South Canterbury builder, who is pushing the discipline to fresh heights.
German David Storl took silver and Czech Republic thrower Tomas Stanek won bronze.
''I did not have even one good throw,'' Stanek lamented.
''It was horrible. If I feel well I could surely secure the silver but I do not think I would beat Tomas today. He was so strong.''
Walsh will head to the Gold Coast Commonwealth Games as the most overwhelming of favourites.
Before that he's returning home for three meets, at Timaru, Christchurch and Waitakere.
