Sahay, a 1975-batch IPS officer of Manipur-Tripura cadre, was already holding the additional charge of the CRPF Director General since October 3 after incumbent K Vijay Kumar retired in September.
Official sources said formal orders in this regard will be issued soon as Sahay's appointment has been okayed by the Appointments Committee of Cabinet (ACC).
He is expected to hold the top CRPF post till his retirement in July next year.
At present, Sahay is also the chief of border guarding force Sashastra Seema Bal (SSB), a post which he is expected to relinquish after official orders are issued in the next few days.
The about three-lakh strong Central Reserve Police Force (CRPF) is the country's mainstay for anti-Naxal operations.
The post of CRPF DG is considered important as the force has not only deployed 80 battalions (about 80,000 personnel) for anti-Naxal operations, it is also fighting militancy in Jammu and Kashmir and North East.
Sahay has a vast experience of working in central paramilitary forces as he had stints in forces like CISF and BSF too.
He had served in the CRPF earlier as the ADG (North zone) between 2007-2008.