In the role, Ashton-Booth will work closely with Aikens on various projects including his Michelin-starred fine dining restaurant Muse that's located in London's Belgravia.
Announcing the appointment on Instagram, Aikens said: "Sam is an exceptional talent and has worked in some great kitchens all across the UK.
"He is a huge part of the team in making everything more consistent and pushing further on the development front at Muse and other projects.
"We are always looking at improving our dynamic hardworking team to strive for greater results in everything we do for our guests."
Ashton-Booth was most recently oversaw the stoves at Robin Gill’s Counter Culture restaurant in London’s Clapham, which closed last year.
Before that he was head chef at Martin Jarvis’ short-lived Stem restaurant in Mayfair, having previously worked as head chef at Jarvis’ debut restaurant Anglo in Farringdon. Prior to that oversaw the kitchen at Tom Sellers' Restaurant Story in Southwark.
Aikens opened Muse in late 2019.
The restaurant offers an experience-led tasting menu that channels Aikens' own childhood memories.
It won its first Michelin Star in January.