Australian DJs Mel Greig and Michael Christian made the hoax call to the King Edward VII's hospital in central London, posing as the Queen and Prince of Wales when Kate was being treated for a rare form of pregnancy sickness.
Nurse Jacintha Saldanha, who transferred them to a colleague, who then described Kate's condition in detail, was found hanged a few days after the incident, sparking a backlash against the 2Day FM DJs.
The Crown Prosecution Service (CPS) today announced that no charges will be brought over the hoax calls.
Malcolm McHaffie, deputy head of special crime at the CPS, said there was no evidence to support a manslaughter charge and any potential prosecution would not be in the public interest.
He said: "As is well known, on December 4 2012 Mel Greig and Michael Christian, both radio presenters in Australia, made a telephone call to the King Edward VII's Hospital in London, where the Duchess of Cambridge was receiving treatment, in which they pretended to be members of the Royal Family.
"During the course of the call, private information about the Duchess's health was given, in good faith, to Ms Greig and Mr Christian and the call was later played on a radio station in Australia.
"Subsequently, Jacintha Saldanha, a nurse at the hospital who had initially taken the call but who had not herself passed on the information, tragically took her own life."
He said Scotland Yard provided the CPS with a file of evidence on December 19 and asked advice on whether a prosecution should be brought.
"Having carefully reviewed the evidence currently available, we have concluded that there is no evidence to support a charge of manslaughter and that, although there is some evidence to warrant further investigation of offences under the Data Protection Act 1998, the Malicious Communications Act 1988 and the Communications Act 2003, no further investigation is required because any potential prosecution would not be in the public interest," he said.
Mr McHaffie said the CPS had taken into account, among other matters, that it is not possible to extradite people from Australia on the potential offences in question.
He also said it considered that "however misguided, the telephone call was intended as a harmless prank".
"The consequences in this case were very sad. We send our sincere condolences to Jacintha Saldanha's family."
Southern Cross Austereo, the parent company of 2Day FM, has since cancelled the radio show involved, the Hot 30 Countdown, replacing it with a new programme called The Bump.
Rhys Holleran, chief executive of Southern Cross Austereo, was reported as saying the show's hosts, Christian and Greig, would return to work "when the time is right".
The pair spoke of their grief on Australian television soon after Ms Saldanha's death, saying their prank had prompted "a tragic turn of events no-one could have predicted or expected".
Mother-of-two Ms Saldanha was found dead in her nurses' quarters three days after she transferred the call from the DJs to a colleague at London's King Edward VII's Hospital who then described Kate's condition in detail.
The 46-year-old, from Bristol, left two notes in her room and had marks on her wrist when her body was discovered on December 7 last year, Westminster Coroner's Court in London heard.
John Lofthouse, chief executive at King Edward VII's Hospital, said: "This morning we have learned that the Crown Prosecution Service has issued a statement regarding hoax calls to our hospital.
"We have no further comment on this matter.
"The consequences of that hoax call are well known, and tragic.
"We will continue to support the family of much-loved nurse Jacintha Saldanha during what continues to be a very sad time."
Labour MP Keith Vaz, who has supported Ms Saldanha's family since the death, said they still had many unanswered questions.
He said: "I am grateful to the Crown Prosecution Service and the Metropolitan Police for their continuing investigation into Jacintha's death. This is obviously a very complex case.
"The family of Jacintha have been left devastated by her death. They are struggling to come to terms with the events that led to it, especially the hoax call.
"The family still have many unanswered questions and now await the inquest due to start on March 26."
Mr Vaz said previously that Ms Saldanha's grieving family had prepared 40 questions for the hospital, as well as a list of questions for Southern Cross Austereo.
But it has been confirmed that the 40 questions will only be answered following an internal inquiry, led by hospital chairman Lord Glenarthur.