The Welshman retained his title against the mandatory challenger at Wembley Arena, and the 26-year-old Cleverly admitted that he did not expect Krasniqi to go the distance after catching him with some good shots early in the fight.
"I was surprised he went the full 12 rounds because I hurt him early on with the right hand and I thought that sooner or later he'd go," the Daily Mail quotes Cleverly as saying.
"But he dug in, was very hungry and kept fighting back. It was important that I stayed focused and boxed.
"At this level it's important to break your opponents down because these are world level fighters, 12-round fighters who are very tough, so you can't be gung-ho and reckless.
"I felt good in there and I'm pleased with the performance, it was a nice boxing display. He was tough."
Elsewhere in British boxing, heavyweight Tyson Fury marked his American debut with a KO victory over Steve Cunningham in Madison Square Garden, while Brian Rose stopped Joachim Alcine in the 12th round in his hometown of Blackpool.