Richard Hall, 70, was killed in cold blood by 22-year-old Stourbridge man Moses Christensen, while he walked on Brown Clee Hill in Shropshire on August 13 last year.
During the trial the court was told harrowing details of how Christensen brutally attacked Mr Hall using a combat-style knife "just for the sake of killing somebody".
Home Office-approved pathologist Dr Brett Lockyer said Mr Hall had suffered 26 injuries, including a "horrific" wound to his hand and another which had penetrated his skull.
The court also heard Christensen, who had armed himself with two combat knives, was being sought by police at the time – after telling a relative he wanted to kill three teachers.
In a statement, the family of Mr Hall, who was from Perton, in Staffordshire, said Christensen was responsible for an "act of pure evil", and that no sentence would give them justice for what happened.
They said: "Richard was a brilliant man in every way, 70 years young, an amazing husband, father and grandad.
"A man with so much to live for whose life was so brutally and senselessly taken away by what can only be described as an act of pure evil, perpetrated by pure evil.
"It beggars belief that this could happen to someone simply talking a walk on a summer's evening in such a remote and beautiful location.
"We as a family have been left shattered by these events and will never fully comprehend what has tragically taken place.
"No sentence imposed by any court could give us complete justice for Richard. A truly wonderful man who was loved, admired and respected by so many people and his memory will never fade. "
Senior Investigating Officer, DCI Mark Bellamy, from West Mercia Police’s Major Investigation Unit, welcomed Christensen's conviction.
He said: “Richard Hall’s family have understandably been left shattered by his loss, Richard was simply taking a walk on Brown Clee Hill when he was tragically killed in a senseless attack.
“Moses Christensen is clearly a dangerous individual and I’m pleased the jury has reached the verdict it has and found him guilty of murder.
"He had no motive to kill Richard Hall other than Richard was sadly in the wrong place at the wrong time.
"Moses Christensen’s violent and horrific actions have left a family without a husband, father and grandad, a man who was respected by many. and our thoughts remain with them at this very difficult time.”
During the trial the court had heard Christensen told police he wanted to kill someone "just for the sake of killing somebody" – as a "sort of lifelong desire and ambition".
Christensen, who has a history of depression dating back to his early teens, was arrested after knocking on the door of a house in the Burwarton area and telling the occupant he had committed a crime.
After informing police called to the property that he had "cut himself whilst committing a murder", Christensen went on to describe how he had seen Mr Hall emerge "out of the fog" on the hill.
Prosecutor Adrian Keeling QC, had told the jury: "In interview he said this: 'I would like to point out that this wasn't just an outburst of emotion or something'.
"It wasn't a spontaneous event. He said he wanted to do it, in his words, silently... without there being any witnesses."
Christensen, who is said to have autism spectrum disorder and had previously spent periods of time living rough in the countryside, denied murder.
Following his conviction, Christensen, from Oldswinford in Stourbridge, was told by Mr Justice Pepperall that he would face a sentence of life imprisonment, as he adjourned proceedings until March 16.
He said: "I am going to delay sentencing.
"But understand this. There is only one sentence that can be passed and that is a sentence of life imprisonment."