Ardern wore a bespoke maternity evening dress by New Zealand designer Juliette Hogan under the korowai, and gave a toast to the Commonwealth in which she used a Maori proverb.
Ardern also caught the Australian media's attention - The Australian wrote that while the Queen was the star of the show at her last Chogm, "Jacinda Ardern's first Chogm has given her almost equal billing."
It said she was a media favourite and had been getting special favours from other leaders - such as a ride with British PM Theresa May to a meeting of the Five Eyes leaders after their bilateral meeting.
It too pointed to the korowai, saying Ardern had "outshone even Mr Trudeau - infamous for his cultural appropriation of Indian traditional costumes - when she appeared in a traditional Maori feathered cloak."
Ardern is now at Windsor Castle for the Leaders Retreat day of the Commonwealth Heads of Government meeting - a day long affair in which only the leaders meet, without officials or staff.
Those leaders are expected to discuss whether Prince Charles will take over as Head of the Commonwealth when he succeeds the Queen as monarch.
The Queen will turn 92 on Saturday and this is likely to be her final Chogm as she hands over travel to Charles. The Queen had put in a plea for that to happen the day before.
Ardern said she intended to support that. "We hold the very clear vote that the Head of the Commonwealth should follow the Crown. It makes sense and I haven't been deterred from that view. I think New Zealanders would probably share the view that would be the natural succession.
"That's how it was started, by the monarch and I think it would be disruptive probably to the governance of the Commonwealth to start an alternate regime. It's served us well until now and I cannot see why it would not continue to serve us well."
In her opening remarks, May said they would also discuss issues such as recent international events such as the use of chemical weapons in Syria.