Liberal Jane Howlett has won the new Tasmanian Legislative Council seat of Prosser to double the party's Upper House representation.
Ms Howlett was declared the victor on Tuesday night more than a week after voters hit the polls, edging Labor's Janet Lambert 8776 votes to 7889 once preferences were distributed.
The Liberals, returned to power at the March state election, now have two seats in an independent-dominated 15-seat Upper House.
Labor has four members.
Premier Will Hodgman tweeted his support, writing the people of Prosser had repeated the "clear message" from the state poll and further endorsed a majority Liberal government.
Former lord mayor and independent Rob Valentine was re-elected in the division of Hobart, the other seat to be decided by the May 5 poll.
The division of Prosser on the state's southeast coast was created in 2017 after a Legislative Council redistribution process.