Andrew Bowering has been jailed for nine years over the house raid and knife attack in Croft Street, Willenhall, last year.
The 26-year-old career criminal broke into the pensioner's terraced house in the early hours of December 27 and carried a TV into the garden before returning inside to steal more.
As he was rummaging through drawers he was disturbed by the 82-year-old man, who he stabbed three times in the legs and once in the head, leaving him with a broken nose.
Neighbours heard Bowering, who was on licence from prison at the time, saying: "Where are your car keys…do you want me to stab you?"
They called police and when officers arrived they found Bowering stripped from the waist down wearing the bloodied T-shirt.
Bowering, of Gomer Street, Willenhall, then undressed and claimed he was the victim's grandson, saying that he lived at the house and had challenged the burglar.
However he was covered in the pensioner's blood and later admitted wounding and aggravated burglary.
He was sentenced to nine years in prison at Wolverhampton Crown Court on Thursday.
Investigating officer Detective Constable Mandy Dorrington said: “This was a brutal, totally unwarranted attack on an elderly man.
"He posed no threat to Bowering yet he lashed out several times with a knife and also left the man with a broken nose.
“Thankfully the victim has gone on to make a good recovery but we could easily have been looking at very serious, possibly fatal stab injuries.
“Our officers quickly saw through Bowering’s claim to be the man’s relative and he was arrested just a few minutes after the attack.
“I wish the victim well for the future and hope the jail sentence handed to Bowering will offer him some comfort."