Harrison is manager of the Majestic branch in Kingston, Surrey, and won the award as the highest-performing Diploma candidate currently working in the UK wine industry.
She was one of seven Majestic employees to pick up awards, presented by chief executive Ian Harris and honorary president Hugh Johnson.
The year was marked by an increase in awards for overseas students, including the winner of the Vintners Cup, Irene Bachkönig from Austria.
Morrisons picked up the Riedel Trophy for the WSET Educator of the Year.
Harris said: “This event is about those who not only seek to be our present and future, but those who have made a recognised step in the right direction in achieving their goals and aspirations.”