Nancy Bikson triumphed in the Chailey and Wivelsfield by election by polling more votes than all the others put together - see below for the full results.
Nancy now becomes a Lewes District Councillor and replaces Cyril Sugarman, who stepped down during the Conservative party re-selection process earlier this year.
The win means that the Conservative party ruling group remains at 20 members.
With a total of 41 Councillors, LDC is also represented by 11 Lib Dems, six Independents, three Greens and an 'Independent Green'.
American born Nancy Bikson moved to Wivelsfield Green in 2013 with husband Eddie to take on the renovations of a Tudor farmhouse, one of the oldest in the village.
She said: "Being entrusted with this house I have always tried to give back to the village and the surrounding area. I have been closely involved with village activities including the church fete, village day and the Christmas group carol evening. I also spend vast amounts of time pounding the lanes and byways with my dogs Milly and Wills.
Nancy is a lawyer by training; she runs Chapel and York, which specialises in helping charities to raise funds internationally.
Nancy Bikson - Conservative 563
Marion Hughes - Lib Dem 324
Nicholas Belcher - Labour 104
Brenda Barnes - Green 60