The Hollywood legend faced Father's Day without his beloved dad Kirk Douglas for the second time, following his death in February 2020.
Michael had paid a heartfelt tribute to Kirk, who died at the age of 103, by sharing a lovely photo of the pair of them together posing by the poolside.
In the caption, the father-of-three wrote: "You will always be an inspiration and I love you with all my heart!"
Catherine was one of the first to comment on the post, responding with a series of red love heart emojis.
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Fans also commented in support, with one writing: "Your dad was an amazing person," while another wrote: "Wonderful photo with two legends." A third added: "Beautiful – your dad was a treasure. Happy Father's Day in heaven to him, and to you."
Catherine Zeta-Jones showed her support for Michael Douglas on Father's Day
While it was a sad and reflective day for Michael, the actor also enjoyed being celebrated by his own children.
The star shares oldest son Cameron Douglas, 42, with former wife Diandra Luker, and son Dylan, 20, and daughter Carys, 18, with Catherine.
Dylan paid a heartfelt tribute to his famous dad on Instagram to mark Father's Day, alongside a throwback childhood photo of himself with Michael.
Catherine and Michael with their children
He wrote: "Dad - every year on Father’s Day I find it hard to articulate how much you mean to me. I should really tell you everyday how much I appreciate you, let alone once a year, but the honest truth is that I can’t find the right words.
"All I can say is that you are my whole world. You are my leader, a role model and someone I aspire to be in every way.
The celebrity couple have a close-knit family
"I can’t imagine a world without you— your advice I hold in the highest regard, and your unwavering support drives me to work hard and believe in myself. I love you so much it honestly hurts. Happy Father’s Day."
Catherine commented on Dylan's sweet post, writing: "What wonderful words from your heart. I love you."
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