Mark Bridger has been found guilty of abducting, murdering five-year-old April Jones and perverting the course of justice.
April vanished while playing on her bike near her home in Machynlleth, mid-Wales, on October 1 last year and her body has never been found.
Today a jury of nine women and three men convicted Bridger, 47, of Ceinws, of abducting and murdering April and of unlawfully disposing of and concealing her body with intent to pervert the course of justice.
Bridger will be sentenced a 2pm
The prosecutor accused him of trying to distance himself from the crime through "a web of lies and half truths".
The disappearance of April, who had cerebral palsy, sparked a massive outpouring of support for her family, with hundreds of people joining in the search.
The jury returned the unanimous verdicts following four hours and six minutes of deliberations.
From the dock, Bridger, wearing a blue shirt and spotted tie, looked nervous before the verdicts were read.
He closed his eyes and appeared to hold back tears as the guilty verdicts were read.
April's parents Paul, 41, and Coral, 43, who have attended every day of the month-long trial, were following the verdicts from the public gallery, on a balcony overlooking the court room. Mrs Jones appeared to wipe away tears as the verdicts were announced.
The verdicts were greeted with complete silence from the public gallery.
Trial Judge Mr Justice Griffith Williams said he would sentence Bridger at 2pm.
The trial, which began on April 30, was told that Bridger was a "fantasist" who had "a clear interest in child pornography and in child murder cases".
The defendant himself had told police he was an SAS-trained "mercenary" but was in fact a former abattoir worker and a failed London fireman - who quit the service after six months because he could not reach the required training standard.
Elwen Evans QC, prosecuting, said Bridger murdered five-year-old April and then played a "cruel game" in an attempt to cover his tracks.
She told the jury: "He claimed to know the rugged terrain around Machynlleth well, and that's been a significant feature in police determining the size, scope and scale in their search for April."
April in the coat she was last seen in
Miss Evans also told the jury about the kind of obscene material which had been found on Bridger's laptop following his arrest.
Police found numerous indecent images on the computer, as well as pictures of young female murder victims, including Holly Wells and Jessica Chapman, the victims of Soham killer Ian Huntley.
Bridger also had images of local young Machynlleth girls, including April and her half-sisters, aged 13 and 16.
"We say his interest in pornography, young girls, rape and murder cases is all too relevant and you may see it as the key to understanding what he did and why he did what he did," Miss Evans told them.
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Mark Bridger Guilty
On the day April was abducted, Bridger had viewed online photographs of a young girl and a pornographic cartoon depicting, Miss Evans said, the apparent rape of a physically restrained and visibly distressed girl.
The same day, his girlfriend had finished with him and he had tried to ask three different women out on Facebook.
It is not known what Bridger said to April to entice her into his car. The court heard she was "happy and smiling" when she was seen climbing into a Land Rover Discovery.
Miss Evans told the jury Bridger's claim that April died in a car accident was lie to cover up his "sexual" motivation for snatching the five-year-old.
Early in the trial, the jury was taken to visit Bridger's cottage, Mount Pleasant, where April's blood and small bone fragments were found.
April's parents Coral and Paul Jones
Those microscopic pieces of April's skull were all that was found, despite the largest search in British policing history and a police investigation which cost in the region of £8.5 million.
Bridger is a "cold-hearted murderer" who "spun a web of lies and half-truths" to try to get away with his "truly horrific" crime, prosecutors said after the verdict.
In a statement, Ed Beltrami, Chief Crown Prosecutor for CPS Wales, said: "We welcome today's verdict, which brings to a close a difficult and challenging prosecution.
"Ever since his first interview with police in October last year, Mark Bridger has relentlessly spun a web of lies and half-truths to try and distance himself from the truly horrific nature of the crime he perpetrated. He has refused to take responsibility for what he did to April and has stopped at nothing to try and cover his tracks.
"Despite his best efforts to evade justice, he has been brought to account by a highly professional investigation by Dyfed Powys Police, coupled with the diligence and hard work of the prosecution team. Working together, we have been able to comprehensively dismantle Bridger's version of events and expose him as a violent, cold-hearted murderer and a calculated liar.
A court sketch on Mark Bridger
"I would like to record our thanks to everyone who supported the prosecution of this case. Everyone who has provided a statement to police or given evidence in court has played their part in today's verdict.
"At the very heart of this case are April's family, who have been through - and continue to go through - an ordeal of appalling magnitude. They have conducted themselves with a humbling dignity throughout.
"We can only hope that today's verdict will be of some help to them as they continue to try and come to terms with the loss of April."