Fekete had a puncher's record - five off his six wins were by knock-out - but Munroe was too big, too strong and hit too hard.
He walked his opponent down, then blasted the Hungarian to his knees with a left-right-left.
Fekete beat the count, but referee Rob Chalmers waved the fight off after just 101 seconds.
"My biggest fight was with the scales and stepping up in weight was definitely over due," said the 32-year-old, who scaled a career-heavy 9st 7lbs 6ozs.
"I retired because I was disappointed with the lack of opportunities I was getting. But I'm back and now it's all about having fun again."
Munroe attracted a sell-out crowd to the city-centre nightclub and could be back in action there in October.
"I leave who I'm fighting down to my management," he added. "But there's no reason why I can't bring a world title back to Leicester."