Mr Cushnahan was one of the key figures in the controversy over the sale of National Assets Management Agency's Northern Ireland property portfolio.
The former banker tried to stop the BBC from reporting on his involvement in the sale.
He has now withdrawn his claims against the BBC.
The claims related to two major Spotlight investigations into NAMA, which were broadcast in February and September 2016.
NAMA took effective control of a property loan portfolio in Northern Ireland worth more than Â£1bn after the financial crisis.
It set up a committee to advise it on Northern Ireland issues and Mr Cushnahan was recommended for appointment by the Democratic Unionist Party.
He served on the committee from 2010 to 2013.
Both Spotlight programmes investigated the circumstances surrounding the sale of NAMA's remaining Northern Ireland loan portfolio, known as Project Eagle.
They also examined the role which, amongst others, Mr Cushnahan played in advising NAMA, commercial bidders for Project Eagle and Northern Ireland-based debtors, whose assets were controlled by NAMA.
Mr Cushnahan's claim for an injunction was rejected in its entirety by the senior judge of the Queen's Bench Division, Mr Justice Stephens, in a judgment dated 10 March 2017.
In his judgment, the judge recognised that "there could be no sensible contention" that the broadcast of the programmes was not in the public interest and that there was a "clear public interest in publication."
Several parts of the claim were also struck out by the judge as an abuse of process, including an attempt to bring action against the Editor of BBC Spotlight for contempt of court.
Following nine months of legal action, Mr Cushnahan dropped his appeal against Mr Justice Stephens' decision on 21 June.
Reporting restrictions put in place at the outset of this case in September 2016 have now been lifted by the court, allowing the BBC and other media organisations to report the matter for the first time.
The BBC has not apologised, paid damages, or any of Mr Cushnahan's legal fees.
In a statement,  Mr Cushnahan acknowledged that his court action against the BBC had not  been successful,  but said he had co-operated at all times with the investigation into Nama.
He also said he now intends to  bring a case against the UK government  to the European Court of Human Rights because he believes that UK law does not provide adequate safeguards to allow him to protect his reputation.
All legal claims brought against the BBC and BBC Spotlight's Editor, Jeremy Adams, by Frank Cushnahan have been dropped.