Planning permission and listed building consent have been granted for the £18m renovation and expansion of Bath Abbey.
At a meeting, Bath and North East Somerset councillors voted overwhelmingly in favour of plans to improve public and administration facilities at the Abbey.
Plans include a new song school, alterations to the clergy vestry and opening access to underground vaults.
Rector Edward Mason said he was "thrilled" permission had been granted.
He said: "The vote is indicative of the strength of partnership of the Abbey with Bath and North East Somerset Council and many other organisations in the centre of Bath.
"It's a shining example of how people can work together for the community's good."
Abbey officials have been in consultation with organisations such as English Heritage, Bath Preservation Trust and the council on the plans for seven years.
Charles Curnock, director of the Footprint project, designed to help develop the facilities at the Abbey, said it was "a very significant day".
"A huge amount of consultation, discussion and listening has gone into this and we're very grateful to everyone for their contributions," he said.
"Together, we want to protect the fabric of this precious building and to make it a space for everyone, and this is a big step towards this goal."
The project is being funded via a combination of church funds, applications to grant-making bodies, legacies and donations.
Work is expected to begin in summer 2014.