His predecessor Lt Gen Dalbir Singh, expected to be the next Army chief, is assuming charge as the Vic-chief of Army Staff in Delhi.
Lt Gen Rai becomes the first 'Corps of Engineer' officer to head one of the leading operational commands whose area of operation includes the seven north-eastern states, West Bengal and Sikkim.
After assuming charge Rai paid homage and laid a wreath at the 'Vijay Smarak' on his arrival at Fort William, the headquarters of Eastern Command.
Prior to this, he was serving as the Chief of Staff, South Western Command in Jaipur.
Rai was awarded Vishisht Seva Medal (VSM) as a Brigadier and Ati Vishisht Seva Medal (AVSM) as GOC of a Rashtriya Rifles Force in Jammu and Kashmir for his devotion to duty and distinguished service.