The authority is also going to crack down on anyone involved in anti-social behaviour or using barbecues on the landmark.
The move has been welcomed by campaigners who have called for the 4,000-year-old Iron Age hill fort in Almondbury to be safeguarded.
It follows fires on the hill and complaints of people driving noisy, souped-up cars on the site.
Pressed for immediate action by Green councillor Andrew Cooper (Newsome), who has suggested installing an automatic retractable bollard on the access road leading to the hill, council chiefs said plans were underway.
“Action is going to be taken on this,” said Coun Rob Walker, the council’s Cabinet member for the environment.
He said discussions were taking place over how signs would communicate the closure.
And he revealed the authority was preparing to step up enforcement to deal with anyone using barbecues and Chinese lanterns.
He added: “We will do our best to stop anti-social and inappropriate behaviour on Castle Hill.
“Stopping everybody going up there on foot is very difficult but we are going to restrict access for motor vehicles in the evenings.
“With the bollards and signage I think there is a wish amongst officers to get this in place as soon as possible.”
He pledged to follow progress and to update local members on when work is likely to be carried out.
Coun Cooper said the council’s decision was “good news”.
He added: “I am pleased a commitment has been made.
“I think people going up on foot are less likely to be anti-social because it’s hard to carry stuff with you.
“Now it’s really a matter of how long it takes. The proof of the pudding is in the idea. We have to see it actually happen.”
Almondbury councillor Alison Munro (Lib Dem) who, alongside her Conservative colleague Coun Bernard McGuin, has called for the site to be protected, also applauded the move.
“It is really good news that after many years of campaigning the council have begun the process to restrict access by motor vehicles to the Castle Hill site at night.”