The celebrity chef had previously revealed his plan to temporarily close the Royal Hospital Road venue in order to reinvent his flagship restaurant and keep the high Michelin-star standards which diners and inspectors expect.
However Ramsay has now announced Smyth, who originally joined the Restaurant Gordon Ramsay team as chef de partie in 2002, will take a share of the business and will invest in the restaurant and the staff in her new role as standing chef-patron.
Following a four-week refurbishment, the restaurant will reopen in early March.
"I'm incredibly proud of Clare and what she has achieved," said Ramsay, announcing the new partnership.
"She is an amazingly talented chef and the time is right for her to build on this. Restaurant Gordon Ramsay will always be very special to me and Clare becoming chef-patron is testament to my partnership with, and trust in, her," he added.
According to press notes, the reinvented Restaurant Gordon Ramsay will represent Smyth's respect for the heritage and legacy of Ramsay's involvement with London's longest running three Michelin star restaurant.
The menu will showcase new creations alongside Ramsay classics such as a lobster, langoustine and salmon ravioli which Smyth describes as 'the perfect dish'.
Smyth plans to keep the traditional drink and cheese trollies but will introduce modern elements too such as a liqueur library and a 'chef experience table' with a bespoke menu.
Meanwhile, the restaurant's new design will take inspiration from Art Deco décor using luxurious materials to 'emphasise the mood' of different spaces within the restaurant.
After three years at Restaurant Gordon Ramsay, Smyth left as senior sous chef to work in various other kitchens around the world and with a number of leading chefs including Alain Ducasse.
She returned to the Chelsea eatery in 2007 as head chef where she has remained, with growing power over the direction of the restaurant, ever since.
“I am hugely passionate about Restaurant Gordon Ramsay and delivering the best possible guest experience," Smyth said.
"Everything we do has to be immaculate – food, wine, service. The refurbishment is Gordon’s and my celebration of all that makes Restaurant Gordon Ramsay so special.
“I am also hugely motivated in the continuation of our commitment to developing and nurturing the next generation of chefs and front of house," she concluded.