The reality TV star looked every inch the doting uncle when he shared the photo on his Instagram page earlier today (May 6).
In the pic, Buzz can be seen looking up at his uncle, while Mario gazes down at his beautiful nephew, with a protective arm around the baby.
Mario isn't Buzz's only famous relative - his dad is McFly (and now McBusted) star Tom Fletcher.
Tom is married to Mario's sister Giovanna and the pair welcomed their baby boy Buzz Michelangelo in March this year.
Got an iPad or iPhone? Reveal Mag is specially designed to fit!
Celebrities who welcomed babies in 2014 in pictures:
Copyright: Rex Features WENN/Matthew Taylor/Daniel Deme/Josiah True/Matthre Taylor/Joe