The STV debate will take place on 5 August between the first minister and the leader of the pro-union Better Together campaign, and will be hosted by the broadcaster's political editor. Bernard Ponsonby.
STV originally set the date for the debate for 16 July, but cancelled it because Salmond refused to take part unless David Cameron was his opponent. The broadcaster then offered the later date, which Salmond immediately accepted, this time agreeing to face Darling. But Better Together, apparently annoyed by what they saw as STV's surrender to the first minister's demands, initially refused to take part. Meanwhile, the BBC made a rival bid to host a live debate in Inverness on 12 August, hosted by James Cook.
As STV confirmed the debate on Wednesday evening, a spokesperson for the first minister said: "We accepted this invitation weeks ago and are delighted that Alistair Darling has finally done likewise and accepted the challenge of debating with the first minister on live TV, in front of a large audience of voters.
"Mr Darling will be acting as a shield for the prime minister – who we will continue to pursue for a debate – and as such he will be defending the Tory policies of David Cameron's government."
The two-hour debate will take place at the Royal Conservatoire of Scotland, in Glasgow, in front of an audience of 350 members of the public.
A spokesperson for Better Together said: "We are delighted that there will be a live, televised debate between the leaders of both campaigns. Alex Salmond will now finally have to answer questions on the pound, pensions and public services that he has spent the last two years dodging."
The announcement comes as the head of the Scotch Whisky Association (SWA), David Frost, has countered claims that business leaders have faced pressure from the SNP not to enter the debate on Scottish independence.
Frost's predecessor at the SWA, Gavin Hewitt, told Channel 4's Dispatches on Monday night that firms feared they could face "retribution down the track" if they spoke out against independence.
Writing in the Scotsman on Thursday, Frost said the referendum debate had been "frank and constructive". He added: "Despite the strong feelings on either side of the debate, we have felt able to participate in what we regard as a constructive manner. All sides have made it clear that our engagement in the debate is welcome, whether or not they agree with our analysis of the potential impact of change on the industry."
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