Kieran Davies, 28, had denied murdering Ashley Hawkins, 32, from Barry in Vale of Glamorgan, Wales, who was found dead in a flat in Scotland Street on 2 December 2016 at 05:30.
Sentencing was deferred for background reports at the High Court in Edinburgh.
Lord Boyd told jurors: "Murder cases are always difficult."
He added: "They are emotionally draining for everybody involved in it."
Police who were called to the second floor flat at 7 Scotland Street and forced entry found Mr Hawkins dead with catastrophic head injuries.
Unemployed Davies was the only other occupant of the locked property and was found topless, wearing jogging bottoms and trainers extensively stained with the dead man's blood.
A Reebok top, which Davies had earlier been seen wearing, was found in a washing machine, saturated with the victim's blood, along with brain tissue.
The court heard Mr Hawkins had suffered at least 24 blows to the head and a metal pole and broken hammer recovered from the flat could have been used as weapons in the fatal attack.
Davies, a prisoner in Edinburgh, was found guilty of murdering Mr Hawkins by repeatedly striking him on the head with weapons and repeatedly stamping and kicking him on the head and body.
Police were alerted to the incident in the early hours of the morning after neighbours heard banging and shouting coming from the flat.
One teenager was aware of 15 to 20 bangs and screaming which had stopped by the end of the disturbance.
The witness was confident that no one left the premises from the end of the banging until the arrival of officers.
Police found the front door of the flat was locked and entry was forced and an attempt was made to resuscitate the victim who was lying face down covered with a blanket and surrounded by a pool of blood.
Prosecutor David Taylor told jurors: "When police came into that locked flat there were two people there - one alive, covered in blood and one dead, violently murdered. There is no mystery in this case."
He said Davies and Mr Hawkins had come to Edinburgh from Wales "as best of friends" but added there was evidence that changed and there was friction between them.
Davies told police that he had taken Valium and claimed that he also had a needle of heroin and ecstasy.
A blood test later proved negative for ecstasy and opiate drugs but gave an indication that he had taken diazepam and cannabis.
Mr Stewart told the court that previously consideration had been given to Davies' fitness to stand trial and a psychiatrist who had seen him reported that he suffered from a delusional disorder.
Det Insp Stuart Alexander, of Police Scotland's major investigation team, said: "Davies continued to maintain his innocence throughout the investigation and trial, despite significant evidence of his guilt.
"When officers found him in the flat, he claimed to have no recollection of Ashley's death and has given no explanation for why he took the life of a friend.
"Davies subjected Ashley to a brutal and sustained attack and we welcome this conviction. I hope this helps Ashley's loved ones as they continue to come to terms with their loss."
Det Insp Stuart Alexander, of Police Scotland, said: "Davies continued to maintain his innocence throughout the investigation and trial, despite significant evidence of his guilt.
"When officers found him in the flat, he claimed to have no recollection of Ashley's death and has given no explanation for why he took the life of a friend.
"Davies subjected Ashley to a brutal and sustained attack and we welcome this conviction. I hope this helps Ashley's loved ones as they continue to come to terms with their loss."
Davies is due to be sentenced at Edinburgh High Court on 24 August.
The former best friend of a man found bludgeoned to death in one of the most exclusive streets in Edinburgh has been found guilty of the murder.