Mews Court was built in the late 18th Century as an addition to the Grade I listed Stable Block.
It has a courtyard surrounded by buildings which were originally designed as accommodation for equestrian staff.
The estate once kept horses on a grand scale, with room for 84 horses.
Sarah McLeod, chief executive officer of Wentworth Woodhouse Preservation Trust, said the repairs should be completed by the autumn.
“We are extremely grateful to Historic England for its continuing support of our restoration projects.
“This latest grant enables us to carry out the urgent external repairs needed to save Mews Court.
“The buildings are in a perilous state.”
