The name choice prompted an outbreak of wisecracking on Friday on Twitter.
Gossip website TMZ said the name appears on a birth certificate at Cedars-Sinai Medical Center in Los Angeles where Kardashian gave birth on June 15, a few weeks before her due date.
"There were rumors floating around a few months ago that Kim and Kanye West might give the baby a directional name … but who thought they would actually go through with it?" it said.
On its website, People magazine quoted an anonymous source as confirming the name.
It also recalled how Kanye West once quipped on Jay Leno's late-night talk show that Easton West would make a good baby name.
The couple might also have been inspired by a 1994 children's book by comedy writer Alan Zweibel about a nine-year-old boy called North who wanders far and wide in a fruitless quest to find worthy parents.
Pending confirmation, and with daddy West releasing his latest album Yeezus this week, armchair comedians on Twitter had a field day – to the point of making North West a trending topic.
"So I'm assuming that North West won't be a One Direction fan?" said one Twitter wag.
Another fancied the notion of R&B songstress Alicia Keys having a child named Car.
Chris Plante, editor-at-large at gaming website Polygon.com, tweeted that he would be "scheduling a future playdate for North West with my future son Power Plante." – AFP