The photo shows Ardern and Neve, both wearing hats, sitting on the beach.
"Just what the doctor ordered," Gayford wrote. "Thanks holiday, that was great."
Earlier this month, Ardern shared a photo of the New Year's fireworks, which she admitted she doesn't often stay up for these days.
"It's not often I stay up to see the new year in these days (not since we had a baby anyway) but this year, I wanted to make sure I saw the back of 2020," she wrote.
"To everyone who helped us get through this year, thank you. While there are plenty of challenges ahead I feel more confident than ever that we're all up for it. Happy New Year Aotearoa!"
The family was also spotted icecream shopping in Tairua on the last day of 2020.