Thicke starred on the hit series "Growing Pains" in the '80s and '90s, acting as America's father.
Tributes from friends and family started pouring in right after the tragic news broke.
Robin Thicke spoke out about the loss on Instagram.
"My father passed away today," he began. "He was the best man I ever knew. The best friend I ever had. Let's all rejoice and celebrate the joy he brought to every room he was in. We love you Alan Thicke. Thank you for your love. Love, your grateful son."
"I spent Monday through Friday for seven important years with Alan Thicke as my 'TV dad,'" he began. "I'm shocked and truly heartbroken today at the news of his death.
"Alan was a generous, kind and loving man. I am so blessed to have grown up with him. Chelsea and I send our love and prayers to his family tonight. We will cherish the memories ... 'sharing the laughter and love,'" he closed, citing the show's theme song.
Jeremy Miller, who played Ben on the show, added that he "loves Alan deeply" and "lost a father and is heartbroken."
Added Joanna Kerns, his on-screen wife, "I am devastated by Alan's passing and will be for some time."