She is the first woman ever to take the title following a live cook-off at the Restaurant Show at London's Olympia earlier today.
Hansom saw off competition from nine other finalists aged between 18 and 23, who were scouted to take part in the contest.
April Lily Partridge, demi chef de partie at The Clove Club, took second place, while Danny Young, junior sous chef at Northcote, was third.
Each chef was given two hours to prepare a three course menu for two guests from a set list of ingredients.
Hansom told BigHospitality it was 'absolutely amazing' to win.
"This is my fourth year in the competition...I've been first second and third. I just started crying [when they called my name] and I'm not really sure why but it was amazing."
She added that this year was the first time she had been 'really happy' with her cooking in the contest.
The Ritz chef impressed the judges with her starter of autumn vegetable salad and chicken liver panna cotta; a main course of Norweigan fjord trout, smoked eel and horseradish tortellini, roast beetroot, sea vegetables and orange dressing; and a dessert of flourless chocolate cake, chocolate semi-freddo, malt mousseline, chocolate roasted peanuts and caramelised banana.
Chairman of judges Mark Sargeant said: "The standard of the competition [this year] has been incredible. It's been so, so close."