Singer Sir Cliff Richard is suing the BBC and South Yorkshire Police after being investigated over allegations of historical sexual assault.
Legal papers were filed at the High Court in London on Thursday.
They list Sir Cliff as a claimant, and the BBC and chief constable of South Yorkshire Police as defendants.
The star, 75, has always denied the allegations, and the Crown Prosecution Service (CPS) said in June it was taking no further action against him.
The decision to sue the BBC and South Yorkshire Police comes after Sir Cliff was the subject of a long-running police investigation based on allegations dating between 1958 and 1983 made by four men.
Sir Cliff was named as the subject of the investigation after police officers searching his apartment in 2014 were filmed by the BBC.
The CPS announced it was taking no further action against Sir Cliff on 16 June on the grounds of insufficient evidence.
That decision was reviewed last month following an application by one of his alleged accusers, but concluded the original decision not to proceed was correct.
After that announcement, Sir Cliff told BBC Radio 2 that "a cloud lifted" when he was informed of the news he would not be prosecuted.
The singer has previously spoken publicly about the investigation and the publicity surrounding it.
In a statement released in June he criticised what he called "vile accusations", adding he was "named before I was even interviewed, and for me that was like being hung out like 'live bait'".
A spokesman for the singer said: "We can confirm that Sir Cliff today issued legal proceedings at the High Court against both South Yorkshire Police and the BBC. It would not be appropriate to comment further."
A BBC spokesman said: "While we haven't received any notification of action, we've said previously we are very sorry that Sir Cliff has suffered distress but we have a duty to report on matters of public interest and we stand by our journalism."