Ms Ardern's partner Clarke Gayford told the New Zealand Herald the cat once interrupted a phone call between the new prime minister and US President Donald Trump.
The Prime Minister's office has confirmed the cat's death, news.com.au reports, and well-wishers have taken to Twitter to express their condolences. However, the doctor declared her dead on arrival. "Paddles was much loved, and not just by us", she wrote.
On Instagram, Ardern thanked everyone for their thoughts and asked people to "please be kind" to New Zealand's Society for the Prevention of Cruelty to Animals.More news: Joshua-Parker: Hearn Will Negotiate Terms Over Next Few Days
An anonymous user set up a Twitter account last month under the name "First Cat of NZ" which posted regular tweets about the cat's famous "mummy" and pictures of the feline.
The man running the account, who's chosen to remain anonymous, described himself as a "PR guy" for Paddles and spoke to RNZ last month about why he created the account and the "really overwhelming" response from fans.
While many can't believe that something so sad has happened, one thing is for sure - Paddles will certainly be missed.
The dog of the USA ambassador to New Zealand, Scott Brown, was among them. "We will be introducing legislation to Parliament to give effect to this week", Ardern said in a statement. Not affurliated with Labour Pawty.