There has been a Manor House at Sledmere since medieval times, but the present Sledmere House history begins in 1751 when Sir Richard Sykes, who had married Mary Kirkby, an heiress to the Sledmere estates, demolished the previous house and built a new one, planting some 20,000 trees on the Wolds about it. Sir Christopher Sykes, 2nd Baronet (1749–1801) greatly expanded the estate. He and his wife bought and enclosed huge areas of land for cultivation, built two new wings to the house, and landscaped the grounds, planting 10 square kilometres of trees. The entire village of Sledmere was relocated. Sir Christopher left a vast estate of nearly 120 square kilometres and a large mansion set in its own 0.8 square kilometres of parkland, which survives in the family to the present day. Sir Christopher also employed Joseph Rose, the most celebrated plasterer of his day, to decorate Sledmere. The result has been called among the finest plaster-work in England.
Very sadly, a catastrophic fire in 1911 left the building a shell and destroyed the Adam-style 1790s interiors. It is said that Sir Tatton Sykes, 5th Baronet was too busy eating one of the milk puddings to which he was addicted to pay much attention, but villagers and estate workers loyally rescued pictures, statues and furniture, china and carpets, and even doors and banisters, including the house's 1780 copy of the Belvedere Apollo. The roof fell in a few moments later. The original designs for the interiors had survived however, and the house was then restored.
The long Library at Sledmere, superbly restored, is one of the most beautiful rooms in England. The Drawing Room and Music Room were decorated by Joseph Rose, the most famous English plasterer of his day. The Music Room contains a fine organ, with a case designed by Samuel Green for the original house in 1751. The Turkish Room was designed for Sir Mark Sykes, 6th Baronet, by an Armenian artist, David Ohannessian, as a copy of one of the Sultan's apartments in the Yeni Mosque in Istanbul. The tiles were made in Damascus under the supervision of Ohanessian. The attached Roman Catholic chapel has a fine ceiling painted by Thomas Errington. It depicts the four winged creatures of the Evangelist in the Chancel, and in the Nave, a variety of birds including a swan, heron, swallow and lapwing.
Sledmere House is set within a park of 3.9 square kilometres designed in 1777 by Capability Brown and executed by Sir Christopher Sykes, 2nd Baronet. The plan still survives in the house. Its gardens include a paved sculpture court (1911), an 18th-century walled Rose Garden, and a recently laid out Knot Garden.
The fashion writer and novelist, Plum Sykes, was married at Sledmere in 2005.
The Big House: The Story of a Country House and its Family, Christopher Simon Sykes, Harper Perennial, London, 2005