The arrangement, thought to be one of the first of its kind anywhere in England, is expected to save both councils money and will allow them to improve the way they share good ideas and initiatives.
Both councils' licensing teams will deal with premises, personal, temporary event notices, gambling and taxi licences.
David Jukes, chairman of Tunbridge Wells borough licensing committee, said: 'It's excellent that we can operate the licensing function in this way. So often much of what we do is duplicated and this arrangement will ensure that we continue to offer good services on a cost effective basis.'
Keith Loney, Sevenoaks DC cabinet member for licensing, added: 'We are constantly looking to find innovative ways of improving our services. This joint venture with Tunbridge Wells BC is one such example that will lead to financial saving and, over time, an improved service.'
The new arrangements are already in place and will run initially for one year.