The diminutive Burger King manager from Maryland wolfed down 26 of the snacks in a mere 10 minutes without a second thought for her thighs.
Thomas picked up $8,000 for winning the World Grilled Cheese Eating Championship at the Planet Hollywood Restaurant in Times Square in New York.
Weighing a mere 100 pounds, Thomas remarkably felt that she still had room.
"I could have done better" she said, adding that she was aiming for 30 sandwiches.
She said she has a naturally big stomach capacity and heavily soaked her sandwiches in water to make them easier to swallow.
Stomach for the fight
Gut instinct - Sonya's world records
8.31 pounds of Armour Vienna Sausage in ten Minutes
5.75 pounds of tempura deep-fried asparagus in 10 minutes
11 pounds of cheesecake
in nine minutes
80 chicken nuggets in five minutes
65 hard-boiled eggs in six minutes, 40 seconds
44 lobsters (11.3 pounds of meat) from the shell in 12 minutes
46 dozen oysters in 10 minutes
Source: International Federation of Competitive Eating
To train she drinks large amounts of water to expand her stomach capacity and practises relaxing her throat.
Thomas estimated that she gained 10 pounds during Wednesday's contest, but says that usually she is "good to go" just a day or two after a competition.
She was pushed hard for her win by Joey "Jaws" Chestnut, who managed "only" 25.5 sandwiches.
However, there was some consolation for Joey, his world record of 32.5 sandwiches still remains intact.
Not that Thomas does not have her own records to boast about. Among other feats she once swallowed 552 oysters in 10 minutes.
Thomas is known in eating contest circles as the "Black Widow", apparently because she has defeated so many larger men.
Asked on her website if some men's pride is dented by losing to such a small woman, she says: "The best professionals in any sport quickly learn a cardinal rule - never underestimate the competition."
Source: Aljazeera + Agencies