He defeated rival Layla Moran by 42,756 votes to 24,564 to take over from Jo Swinson.
Willie Rennie says he is trying to entice the party's former UK leader to run in next year's Scottish Parliament election.
The Ross, Skye and Lochaber MP has been unanimously re-appointed at the parliamentary party's AGM.
She only became leader of her party in July but has been unseated by the SNP's Amy Callaghan.
All the main UK-wide parties have now revealed their pitches to voters ahead of December 12.
The Scottish Lib Dem leader told STV's Scotland Tonight that his party wants to stop both.
The Liberal Democrat leader has succeeded in a bid to stop the SNP from distributing a leaflet.