Bracknell Forest Borough Council's planning and highways committee approved West London Mental Health NHS Trust's plan for the two and three story care buildings last Wednesday.
The new ward will mean the demolition of the 150-year-old staff offices and loss of many trees.
Up to 72 patients can be accommodated in the unit which was selected on the recommendation of the Govern-ment because of Broadmoor's high security status.
The buildings will surround an enclosed garden and be used for therapy and administration of dangerous people with severe personality disorders (DSPDs).
Unhappy with the application, Cllr Gareth Barnard said at the meeting: "I cannot support this. If you take down the trees it will leave a bleak site.
"It is clear what the purpose of the new building is. It will look a very unsympathetic building — it is just wanton vandalism. The owners of the hospital should have been a lot more sympathetic."
Cllr Langdon Jones agreed that there would be a significant loss of trees and pointed out that it would have a "devastating" effect.
Cllr Andy Blatchford added there would be an "environmental impact" to residents of the hospital and the building should be put in "isolation".
Cllr Tony Flood said
he would vote against the plans as he does not want a building of this kind in the borough.
"What this borough desperately needs is a hospital."
Committee chairman Cllr David Worrall said: "We have one of the top hospitals for psychiatric care, I will be
supporting the motion. The loss of trees when there are very few alternatives is not a high price to pay."
The final vote was 13 to four against.
Paul Robertson PR manager for Broadmoor explained it was "complicated" to predict how many jobs would be created from the new ward.
"We are waiting to see
what happens with the pilot scheme and we won't know
if staff models are right or wrong until then," he said.