Walsh threw a season's best 22.14 metres, while Gill produced his best throw in seven months as he chucked 20.96m.
Both achieved the qualifying standard with their first throw.
Jacko Gill is elated with the ease in which he qualified.
"It's perfect, I've never qualified in my first throw before... Even through juniors or anything, so I couldn't have asked for more. It's really ideal."
Compatriot Walsh got an early mental advantage over American rivals Ryan Crouser and Joe Kovacs, topping the qualifying standings.
"I'm really happy with the ease of the throw and the smoothness of it. It bodes well for tomorrow night [Monday morning NZT].... I was just concentrating on the freedom, moving really well off the back and keeping nice and full. It was just so smooth and exactly what I needed."
Athletics New Zealand's captain for the World Championships is just as excited for his compatriot as he is for himself.
"It's really good for him to get through on a number one throw, every time he comes to a major event he keeps getting better and better and to have two kiwis in the final is great."
Olympic champion Crouser threw 20.90m, while Rio 2016 runner up Kovacs advanced with an effort of 20.67m- below the automatic qualifying mark of 20.75m.
Meanwhile, New Zealand hammer thrower Julia Ratcliffe's upbeat despite a brief appearance in her first major meet wearing the black singlet.
The Princeton University student threw a best of 64.72 metres which wasn't good enough to advance to the final.
Ratcliffe's heave was over five metres below her personal best, and she was frank about her effort.
"Performance wasn't great, but im not going to cry about it. I've got World University Games in Taipei in a couple of weeks so I've just got to turn things around and have a bit of a redemption tour over there."
