The military has started clearing of built-up areas of the militants, said a security official on condition of anonymity.
The ground attack started at 6 pm and focused on the main Bazar area in Miranshah where the Pakistani Taliban has a strong presence.
The numbers of casualties was not known as yet.
Operation Zarb-e-Azb was launched on June 15 and the army is trying to mop up the major areas before start of the Muslim holy month of fasting next week.
It has also displaced over 450,000 people who have taken up temporary residences in nearby towns of Bannu, Lakki Marwat and Dera Ismail Khan.
The presence of civilians had delayed the start of ground offensive but it seems that the critical stage of a full-fledged involvement of ground troops has started.