Buddhists celebrate Diwali by lighting lamps and celebrating Gautam Swami Buddha.
Diwali is the auspicious day on which Emperor Ashoka — after what is known as his killing spree in the Battle of Kalinga around 265 BC — decided to follow the path of Buddhism. Buddhists celebrate both Buddha as well as Emperor Ashoka on Diwali.
Emperor Ashoka started the Digvijay campaign on this day, thus the public had greeted them by burning lamps.
Also in Buddhism, after 18 years, Gautam Buddha returned to Kapilavastu with followers. Then Diwali was celebrated by burning millions of lamps in their reception by the citizens. During his first discourse, Buddha gave a new dimension to Deepawali (Diwali) by preaching: "Atha Deepa Bhava".