Simmonds will take up the position of executive chef at The Alpha Club when it opens in May.
He will be responsible for the operations and menu design of the restaurant, but will not be the day-to-day chef in the kitchen.
The announcement comes after the chef confirmed the closure of his Soho pop-up on Tuesday (23 January) after nine months.
Simmonds tweeted: “The Test Kitchen, my temporary pop-up on Frith Street has now come to an end. I’d like to say a huge thanks to everyone that has dined with us and our regulars for their continued support. I am looking forward to the next chapter together.”
The pop-up was designed to act as a test-bed for a permanent restaurant, with diners invited to fill in a feedback card at the end of the meal.
It was subject to a memorably tough review from The Observer’s Jay Rayner, who described the meal as ‘joyless’ and full of ‘salt hits’, but Simmonds told BigHospitality last year that he had taken the criticism in his stride and changed the price point and portion size as a result.
It is understood the chef - who won Michelin stars at Ynyshir Hall and Danesfield House - is still looking to open a permanent iteration of the restaurant, but has yet to secure a site.
Speaking to BigHospitality last summer Simmonds said he was eyeing locations in Marylebone to open a restaurant based around a large chef’s table.
Simmonds joins the Alpha Club alongside Restaurant Association president Robert Walton MBE, who will act as director of hospitality.
The Alpha Club is described as a ‘private members' club for ambitious professionals’. Milton Keynes will be its first site outside of London.