The ward, which serves villagers of Folkingham, Billingborough and Horbling, had been represented by Independent councillor Jan Hansen until he announced he was stepping down in November.
The by election was held yesterday, Thursday, contested between Murray Frank Turner (Liberal Democrat) and Anthony Philip (Tony) Vaughan (Conservative.
Mr Turner was elected with 253 votes. Mr Vaughan received 170 votes.
The turn out was 20.83 per cent.
This means the Liberal Democrats now have three seats on the council, aligned with the seven seats of the Independent Group, the largest opposition group to the 38 seats held by the Conservatives.