After gruelling finals held by the legendary French gastronomic society, both winners were revealed during a ceremony at the Dorchester hotel in London.
In the 35th year of the competition, the UK head of the society, Bailli Délégué Phillip Evins, said the quality of the participants had been extremely high.
"The knowledge, creativity and professionalism of every entrant never fails to amaze and impress the judging panels and although we can only have one winner in each category, all the finalists should be proud of making it as far as they have."
"I would especially like to congratulate Bardary and Marshall, who were up against some very fierce and talented competitors. It is always daunting to have to perform in a competitive environment but they both held their own and thoroughly deserve their winning positions," he added.
Scooping Young Chef of the Year accolade, Marshall beat Lee Warren from Chartwells, part of the Compass Group, at Haileybury and Neil Bell from the Turnberry resort in Scotland.
The finalists were tasked with cooking a three-course meal for four in three hours using ingredients from a 'mystery market basket'. Marshall's winning menu, which was praised for its presentation, originality and taste, included a pan-fried bream starter, loin of lamb main course and orange and thyme panna cotta dessert.
Bardary beat Loic Avril of Heston Blumenthal's The Fat Duck in Maidenhead and Roumain Bourger of The Vineyard in Newbury to the top spot in the Sommelier competition.
All 12 sommeliers faced three tests examining service skills, champagne service and food and wine pairing.
Both winners will now also represent the UK in the international competition which for sommeliers is in South Africa and for chefs will take place in Berlin.
Entry to both competitions is limited to chefs and sommeliers aged 27 or under who have lived in the UK for at least three years. Candidates must be nominated by their employer which must be a member of the Chaîne des Rôtisseurs.