Mr Rai will replace Mohsin Hasan Butt, who served in the province for more than two-and-a-half years.
Mr Rai is a senior police officer of the Pakistan Police Service. Before his new assignment, he worked as chief of the Counter-Terrorism Department (CTD), Punjab, for six years.
Sources said that his appointment as Balochistan IG was made in view of the recent terrorist incident in which 11 Hazara coal miners were killed by assailants in the Mach coal field area of Bolan district two weeks back.
Mr Rai played an important role in elimination of terrorists and their facilitators in Punjab during his six-year term as Punjab CTD chief.