Adil and Mutjaba Ijaz carried out the attack in November last year, moments after they spotted a man in the street they believed had been involved in burgling their family home two weeks earlier.
The suspected burglar was with others when they confronted him and this triggered violence during which Adil Ijaz was knifed in the buttock, Wolverhampton Crown Court was told.
The 25-year-old did not see who stabbed him but thought it was someone who had been standing behind him at the moment he was wounded - and not the man who was recognised from the burglary - said Mr Hugh O'Brien Quinn, prosecuting.
Adil and 27-year-old Mutjaba Ijaz chased after the suspect as he fled down the street and sought sanctuary in the Spar convenience store in Queslett Road, Walsall, on November 15.
He lay on the floor in a bid to stop the door to the shop being opened but the two brothers forced their way in and rained blows down on him, knocking goods off the shelves as the violence swept down aisles.
Two female members of staff and a woman customer took refuge behind the counter but had to hide elsewhere when the victim barged into them while trying to escape the beating.
The brothers, one of whom was armed with a bottle, continued the battering, with one of them holding the man while the other delivered the punches until they phoned their 49-year-old father Waseem.
He came to join in the violence after arming himself with a length of plastic shelving.
The victim did not make a complaint about the beating and refused to engage in the legal process.
The three, all of Brackenfield Road, Great Barr, admitted assault
Ms Laura Miller, defending, said the brothers who, like their father, were of previous good character, each had university degrees, good jobs and a bright future.
But Adil Ijaz and Mutjaba Ijaz were each jailed for ten months by Judge James Burbidge QC who said: “Your big mistake was taking the law into your own hands.”
Their father received a six-month prison term suspended for a year and was ordered to pay £1,000 to the damaged shop.