The Auckland DJ, 22, is dating 23-year-old Renee Brown.
While not naming his new beau, Key posted an image to Instagram with the caption "Call me Joseph Parker coz (sic) I'm punching," meaning he is punching above his weight.
If the Auckland beauty looks familiar, it's because she is the ex-girlfriend of Black Caps cricketing star Mitchell McClenaghan. The pair dated for several years from 2012, and happily flaunted their relationship in a woman's magazine interview in 2014.
Brown, a former architecture and psychology student, has just returned to New Zealand after two years living in Melbourne.
She and Max spent the New Zealand summer together, celebrating New Year as a couple, holidaying in the Coromandel and attending music festivals.
Max shared a very public relationship with his former university student girlfriend Amelia Finlayson back in 2015.
He proudly supported the aspiring model while she competed in the Miss Auckland competition that year.
The pair were critisised at the time for flaunting their lavish lifestyle while John Key was still in office. The former Prime Minister was caught in the crossfire when he appeared in a video of Max's documenting his summer with his girlfriend in Hawaii and Auckland, with detractors accusing the Prime Minister of being out of touch.
The timing of the video was unfortunate, appearing in the same week that New Zealand's unaffordable housing crisis was dominating headlines.
A tongue-in-cheek petition was anonymously launched on Change.org following the couple's split in January 2016.
Titled 'Help Max Key and Amelia Finlayson get back together' and operating under the guise of benefiting The Max-Amelia Memorial Foundation, the petition urged people to support their cause for the sake of the country.
"Without the Max and Amelia duo, certain disaster could soon be on the horizon for NZ," the petition stated.
"With the two separated, it is unknown just what damages will spill over into the current National Government led by John Key, Max's father."
"Please, petition the Key family, in particular John Key (PM) and all the National representatives in the NZ Government to help bring the loving pair back together."