Joyce told Australia's lower house he would remain in his position until the matter was resolved.
He said he was shocked to learn he could be a citizen of New Zealand by descent through his father.
Cue hilarious memes and social media posts.
A photo of Joyce grinning from ear-to-ear while holding aloft a sheep at a campaign photo op "proved" his Kiwi-ness, one online post said.
The obvious jokes about our Kiwi affection for sheep were made easier by Joyce growing up on a sheep farm in Tamworth, NSW.
Numerous jokers inserted him into a well-known "beached as, bro" internet cartoon, superimposing his head on to the New Zealand-accented whale.
Others referenced his notorious feud with actor Johnny Depp, which started when the star and then-wife Amber Heard sneaked two dogs into Australia past quarantine.
Joyce threatened to have the dog euthanised if they didn't leave and the couple were forced to make an apology video that doubled as a quarantine ad.
References to kiwifruit were also popular.
Another user referenced the infamous 1981 "underarm incident".
"Hey, Barnaby Joyce. This make you mad?" the Twitter user jokingly asked.
Another photoshopped picture showed Joyce looking in horror at Frodo Baggins' Hobbit Hole from Lord of the Rings - shot in New Zealand - filled with kiwifruit, All Blacks players, Russell Crowe, and pavlova.
Several people also noticed the uncanny resemblance Joyce bore to Wal from Footrot Flats in a photo of him pairing his akubra with short shorts.
A more straightforward gag drew Maori tribal tattoos on Joyce's face.
Joyce would be the third Member of Parliament ousted over dual citizenship issues, after Greens senators Larissa Waters and Scott Ludlum.
"I was born in Tamworth, just as my mother and my great-grandmother was born there 100 years earlier,' he told Parliament.
"Neither I, nor my parents have ever had any reason to believe I may be a citizen of any other country.
"I was born in Australia in 1967 to an Australian mother and think I am fifth-generation. My father was born in New Zealand and came to Australia in 1947 as a British subject. In fact we were all British subjects at that time.
"Neither I nor my parents have ever applied to register me as a New Zealand citizen, and the NZ Government has no register recognising me as a NZ citizen."
