The brother and sister duo took to social media to share tributes to Terri and the late Steve Irwin.
“Soulmates. Happy Anniversary to my sweetheart parents. Your love is the stuff of miracles,” Bindi, 22, tweeted alongside a photo of the couple.
“Thank you @BindiIrwin. Today marks 29 years since I married your dad. He was a lot of amazing things, but most of all he was fun. Really, truly fun!” Terri, 56, responded.
Meanwhile, Robert, 17, shared a silly photo of his parents which featured an injured Steve sitting in a wheelbarrow with Terri at the helm.
“Happy anniversary, Mum and Dad. (This is my favourite photo ever),” he captioned the pic on Twitter alongside a smiling and red heart emoji.
The Irwins tied the knot in 1991, just eight months after meeting each other. They enjoyed a 14-year marriage and had two children together.
Steve Irwin, widely known as the Crocodile Hunter, died in 2006 after he was struck in the heart by a stingray.