The Home & Away alum concluded: "I’ll miss you beyond what I can put into words. Thankyou mum and John for being his true family and for loving him more than the air we breath! My boy.. I appreciate you!"
Luke was quick to be flooded with support from his industry pals and fans.
"So sorry mate! They are family. Sending all the love 👊," Sunrise weatherman Sam Mac penned in the comments.
The I'm A Celeb alum has been posting Ollie regularly on his Instagram since 2012. He also owns an Aussie Shepherd named Dash.
Just last week, the 41-year-old shared a couch-side picture with Dash as he watched the AFL.
"Saturday afternoon, chilling watching the Swanies with my mate Dash. Let’s #goswans
@sydneyswans #aussieshepherd #afl #kayo #bloods," the actor penned.
The sad news comes not long after the Dancing With The Stars alum celebrated his 41st birthday, with his fiancée Raychel taking to her own Instagram to pen the performer a sweet tribute.
Sharing a collage of some of her favourite photos of Luke, she wrote: "Happy Birthday to my other half!! I’m forever grateful to be by your side and to celebrate this day with you. Definitely a good egg 😘 LOVE!! @lukejacobz."