The post quickly garnered mountains of support from his former Summer Bay family, as well as other famous faces.
Emily Symons penned in the comments: "Sending so much love to you Johnny ♥️💪🏼♥️."
Meanwhile, Georgie Parker added: "❤️❤️❤️❤️🙌 love to you mate," while James Stewart penned: "Fuck c--cer!👊🏽 good on ya Johnny!"
Masked Singer judge Dave Hughes also added his support to the mix, writing: "Your smile inspires the world legend."
And Morning Show host Larry Emdur commented: "Luv ya mate. Punch on 👊👊👊👊 and smash this !!!!! @johnny_ruffo."
Johnny's partner Tahnee also marked the day on her own Instagram, sharing a slideshow of photos and writing: "Five years on 💜 In awe of you every single day.
"Still a huge battle ahead but a major milestone reached that was at times uncertain. Grateful for you always @johnny_ruffo."
The X Factor alum was quick to comment on the tribute, jotting: "5 years to the day and I'm still so grateful for every day I get to spend with you ❤️ ❤️."
WATCH: Johnny Ruffo returns as special guest on Dancing With The Stars
The couple's close friend Lynne McGranger shared her support for both Tahnee and Johnny, writing: "Love you guys ❤️❤️❤️."
Johnny was originally diagnosed with brain cancer in 2017 and later revealed he was all-clear of the disease in 2019.
But in an Instagram post in November 2020, Johnny shared the devastating news that his cancer had returned.
"After an unexpected week of seizures and excruciating headaches it is with a heavy heart that i have to let you know i now have another huge battle ahead of me as my brain cancer has returned," he wrote alongside a photo of himself and Tahnee.
He continued: "Though i will dig deep and beat this sh-t disease again #f-ckcancer."
Since then, the actor has kept fans in the loop when it comes to his cancer journey.
In April this year, the performer delighted his followers with a surprise return to Dancing With The Stars: All Stars.
Sporting an all-black ensemble, complete with a suit and tie and top-hat, Johnny took to the floor with his dance partner Masha Belash, who was donning a stunning green dress.
The couple elicited a standing ovation following their jazzy routine, performed to the song The Business of Love by Domino.
"It was brilliant; it was inspirational. It was so great to see you back up there, you're such a champion mate, we love you to bits," judge Todd McKenney told him.
This article first appeared on our sister site, Now To Love.