"Look ... just accept it ... she's awesome. Is it time to make Australia and New Zealand into one country with @jacindaardern as PM?" Crowe tweeted.
"Not trying to be controversial ... just practical."
Crowe's tweet left social media divided, with Ardern, Australia and New Zealand receiving mixed emotions.
"You can't have her. Besides you need to sort your mess before you're allowed with the in-crowd. #Manus #Kiwis2ndClass #Adani #ClimateChange #1stNation #MeToo
When they're fixed call @jacindaardern and she'll consider you becoming the West Island" one Kiwi wrote.
One Australian wrote: "Well said mate! She's no dill! She makes a lot of our Pollies look like a conga line of cumquats. Very Impressed!"
Australia and New Zealand have often fought over who created the pavlova, successful thoroughbred racehorse Phar Lap, popular band Split Enz and Russell Crowe.
The merger suggestion comes just days after Ardern addressed the United Nations General Assembly.