Britain's Court of Appeal denied Janan Harb's claim for some the king's estimated $85 billion fortune, saying such a claim is only valid when both husband and wife are alive, the BBC said.
She also lost a claim under the Inheritance Act, as the three judges said the king was not a British resident.
Before he died in August at the age of 82, the king's lawyers originally claimed sovereign immunity from the action, arguing heads of state were protected against such action in the courts of another country.
The appeal judges also refused permission to take the case to the House of Lords.
Swim Week Miami Beach 2014 [PHOTOS]