The hotel was sold by the Belfast-based Mooney Group who had owned it since 1986.
The McKeever Group owns a portfolio of hotels which includes the Adair Arms in Ballymena and the Dunsilly in Antrim.
Bookings at the Dunadry are not affected by the change of ownership and all employees will be retained.
In 2016, the McKeever group made a pre-tax profit of just under Â£1m on turnover of Â£8.2m.
The Dunadry Hotel in County Antrim has been bought by the McKeever Hotel Group for an undisclosed sum.