Max Key has posted on Facebook, praising his dad for being "the best role model I could've asked for".
The tribute was posted on Monday evening, after John Key stepped down as Prime Minister.
"Today marks the end of an era," Max wrote.
"To say that I'm proud of you would be an understatement. You achieved your childhood dream and showed me that dreams can really be achieved."
Max acknowledged some of the controversy his father had faced during his tenure as Prime Minster, stating "politics is an inherently polarising industry and therefore the journey was not always the smoothest of sailing".
"In saying this, you always kept your head held high and always remained infectiously positive."
Max has a strong social media presence, with more than 15,000 followers on Facebook and an extensive Snapchat following.
The post had almost 5000 Facebook reactions and 150 comments within the first hour of posting.