"I bow to Mahatma Gandhi on his birth anniversary," Modi tweeted.
"Gandhiji's thoughts and beliefs remain a great inspiration for us. Let us dedicate ourselves to building the India of Gandhiji's dreams," he said.
Modi visited Rajghat shortly before launching his Swachh Bharat Abhiyan that aims to clean up India in five years.
Modi had said that a clean India would be the best tribute to Mahatma Gandhi on his 150th birth anniversary in 2019. Oct 2 is Gandhi's birth anniversary.