This is the first time the hospitality group has appointed a PR agency for The Alchemist brand. Living Ventures' other bar and restaurant brands include Artisan, Blackhouse, New World Taverns and Red Door.
Turn Key's brief is just for the Leeds site, but there is potential for further launches in other regions. The Alchemist currently has sites in London and Manchester.
The new site on Greek Street will be the second Alchemist bar in Leeds.
Simon Potts, managing director of The Alchemist, said: "Turn Key came to us with some really creative ideas and plenty of industry experience – we look forward to working with the team."
Emma Streets, PR and social media director at Turn Key, said: "This is a significant client win for Turn Key. The bar and restaurant scene is crowded in Leeds, but there is a huge opportunity to push creative boundaries, particularly with such a strong brand as The Alchemist."
Turn Key has offices in London, Leeds and LA. Its clients include BP, Cloud Nine, British Land and Hammerson.