Sir Malcolm Bruce has been elected as the new deputy leader of the Liberal Democrats.
The veteran MP - who has already announced he is standing down from the Commons next year - beat competition from colleagues Lorely Burt and Gordon Birtwistle.
The contest, decided by a vote of MPs, was triggered after Simon Hughes quit to become a coalition minister last month.
The victory for Sir Malcolm, MP for Gordon and chair of the Commons International Development Committee, comes with the Lib Dems still in turmoil over claims that former chief executive Lord Rennard sexually harassed female activists.
The peer, who denies any wrongdoing, has been suspended from the party and is facing a fresh disciplinary process for failing to apologise to the alleged victims.
Leader Nick Clegg has also been forced to defend his actions in relation to accusations of "unwelcome sexual behaviour" by Portsmouth South MP Mike Hancock towards a constituent with mental health issues.
Mr Hancock was suspended from the party after the leaking of a QC's report into the allegations - which he denies - three years after the Lib Dems were made aware of the complaints.
He had already resigned the parliamentary party whip last year, but was still sitting as a Lib Dem local councillor.
Some had suggested that victory for Ms Burt - an aide to Treasury minister Danny Alexander - would demonstrate that the party was not hostile to women.
Posting on Twitter, Solihull MP Ms Burt wrote: "Not the result I hoped for but congratulations to @malcolmbruce who won by 2 votes... thanks to all supporters."
Mr Clegg said: "I'm delighted to welcome Malcolm to the post. He is admired across the party for his experience and his ability to keep a cool head - exactly what we need as we head towards the election."
Sir Malcolm, 69, said: "I thank my parliamentary colleagues for the confidence they have shown in me.
"I am looking forward to working with Nick Clegg's team using my experience in and out of Parliament to project a strong and coherent Liberal Democrat message.
"We came into government to rescue the country from economic disaster. Thanks to the Liberal Democrats we are on the road to recovery, income tax has been cut for millions, pensions have had their biggest ever increase and we have moderated the excesses sought by some Conservatives.
"The country does not need Labour to blow it away by reverting to their old habits, unbridled Conservatism to divide our society or the excesses of nationalism to destroy UK cohesion.
"The Liberal Democrats are a constructive and progressive force with the experience and commitment to build a stronger economy in a fairer society enabling everyone to get on in life."