"I have always found Rashtrapati ji to be sensitive towards the aspirations of 125 crore Indians, especially the poor and marginalised," PM Modi tweeted.
"Birthday wishes to Rashtrapati ji. May Almighty bless him with a long and healthy life devoted to the service of our nation," the Prime Minister said in another tweet.
PM Modi called the President "simple & compassionate," adding that he was "sensitive towards the aspirations" of the Indian people.
"Since his tenure began Rashtrapati ji has endeared himself to the people of India through his simple & compassionate nature @rashtrapatibhvn," he wrote.
President Kovind was born on October 1, 1945, at Kanpur Dehat in Uttar Pradesh.
Kovind, who was elected as the country's 14th President, was sworn in on July 25 this year.