Former Borders police commander Watson McAteer wrestled one of the three Hawick and Denholm seats on the council from the Tories as an independent.
Thursday’s by-election resulted from the death, in February, of Zandra Elliot who was elected as a Conservative in 2007.
Mr McAteer, who stood without success as a Lib Dem in 2012, topped a seven-candidate poll. Conservative Trevor Adams finished second, although his party’s share of the vote increased.
At stage one, the count was: McAteer 732; Adams 622; Ian Turnbull (Lib Dem) 450; Harry Stoddart (SNP) 419; Marion Short (Ind) 326; Davie Paterson (Ind) 250 and Craig Bryson (Ind) 74. Bryson was excluded at stage one and Paterson at stage two. The final result was: McAteer 803; Adams 638; Turnbull 485; Stoddart 461 and Short 385. Turnout was 39.25 per cent.
Councillor McAteer joins Alastair Cranston (SNP) and Stuart Marshall (Ind) on the three-member ward.
He commented: “During campaigning, a great variety of issues were raised and I look forward to working with my fellow councillors to tackle them. My priority is to be accessible to all the community.”