The Pole and the Monacan eased past Frenchmen Benjamin Bonzi and Arthur Rinderknech 6-1, 6-4 in their quarterfinal match on Tuesday.
Up next for Zieliński and Nys at the Grand Slam tournament in Melbourne is the French duo of Jérémy Chardy and Fabrice Martin.
Meanwhile, Poland's Magda Linette is set to take on the Czech Republic's Karolina Plíšková for a place in the last four of the women's singles at the Australian Open.
Linette is the last Pole still standing in the singles at this year's Australian Open, which runs until Sunday.
Poland's world No. 1 Iga Świątek has crashed out of the tournament, after being eliminated by Elena Rybakina of Kazakhstan in the fourth round of the women's singles.
On the men's side, Poland’s Hubert Hurkacz bowed out of the tournament after being bested by American Sebastian Korda in the fourth round of the singles at Melbourne Park.
Source: IAR, PAP