Paul Smith was beaten by Tyron Zeuge in a bout for the WBA world super-middleweight belt.
It was Smith’s third attempt to win a world title, all of which have ended in defeat.
Zeuge retained his belt with a unanimous points decision.
The three judges in Wetzlar, Germany, each ruled the fight 119-108 in Zeuge's favour.
Smith, 34, lost WBO title bouts with Arthur Abraham in 2014 and 2015, and trainer Joe Gallagher said Saturday's fight was a "last roll of the dice".
It is the seventh time the Briton has been beaten in his 45 professional fights.
Germany’s Zeuge dominated proceedings in front of a home crowd. Smith was given a count by the referee in the closing seconds of the final round despite appearing to slip.
Promoter Eddie Hearn said to Sky Sports: “Is it the end at world level for him? 100%. Is there another level he wants to compete at? That is one for Paul Smith.
“We talked about last-chance saloon before the fight, he left it much too late. I think he will be kicking himself for that.”