"Saira and I will spend the day in quiet acknowledgement of what we mean to each other, now more than ever, Inshallah," the ailing 90-year-old posted on his Twitter page.
Acknowledging his fans and friends' wishes over the years, his post read: "Each year of our marriage has been made beautiful by everybody who wish us through letters, phone calls and Internet.
"Praying in gratitude for all that Allah has blessed us with his bounty and benevolence. A million thank you for your prayers."
Dilip Kumar, an icon of Hindi cinema with a career spanning six decades, has played both hero and character roles.
Some of his best works are Jwar Bhata, Mela, Naya Daur, Tarana, Devdas, Ganga Jamuna, Leader, Mughal-E-Azam, Shakti, Karma and Saudagar. His last movie was the 1998 film Qila.
In 1966, he married Saira Banu, over 20 years his junior and his co-star in films like Gopi, Sagina and Bairaag.
She has stood by him through thick and thin. Even as her husband has been in and out of hospital due to his age and ailments, she has proved to be a strong support system for him.
Last month, Dilip Kumar suffered a heart attack and was admitted to the hospital. He was discharged after 12 days.