Earlier, Punjab Chief Secretary Sarvesh Kaushal sought the permission of the Governor to start the oath taking ceremony, an official spokesman said.
Soon after being sworn in, Lt Gen Gill (Retd) signed the oath, which was counter-signed by the Governor.
Meanwhile, Chief Minister Parkash Singh Badal also graced the occasion.
Members of Punjab Cabinet and PPSC besides senior officers of civil and police administration were also present on the occasion.