John Lamont received the unanimous support of the party members at a packed meeting in St Boswells on Monday night.
Mr Lamont said: "I am greatly honoured to have been re-adopted as the Scottish Conservative candidate. It has been a great privilege to have served the people of Roxburgh and Berwickshire during the last few years and I look forward to continuing to work hard on their behalf in the future.
"As we approach the next Scottish election, the key issues will be local jobs, transport links, housing and the rural economy. These issues are regularly raised with me as the local MSP. It is critical that we continue to have someone that understands these concerns and can stand up for the Borders in Parliament."
He added: "However, with the Scottish constituencies being enlarged, I now look forward to working hard on behalf of residents in Selkirk and the Ettrick and Yarrow valleys. The constituency might be larger but my commitment to every community, no matter how small, will remain."
John Greenwell, chairman of Berwickshire, Roxburgh and Selkirk Conservatives said: "I am delighted that our members have backed John so strongly. I have rarely seen anyone who is so committed to the Borders and he demonstrates this everyday when he speaks for us in Parliament."