The judges scored the fight 115-113, 116-112 and a wide 117-111 all in favor of a jubilant Kessler.
Froch wasn’t happy with the “hometown” decision, and suggested if the fight had been in the UK, the result might have been different.
“Had the fight been in Nottingham the decision would have gone my way,” said Froch, who is due to become a father in June.
“I took some big punches off a big puncher. But all credit to him he is a proud warrior, I thought it could have gone either way.”
“I’m devastated to lose my title and my unbeaten record. Gutted. But I’ll be back, I’ll definitely be back.”
Robert McCracken, Froch trainer refused to make any excuses, and was quick to defend Froch.
“It was a close fight,” he said. “Kessler was wobbled three times, but Carl didn’t follow up his attacks, but he will learn from it, I just hope the knockers realise he is an outstanding fighter. There’s more to come from him.”