Omar bin Laden, 28, lost his appeal against Britain's refusal in April 2008 to allow him to move here with British-born Zaina Alsabah, 54, who he claimed to have married in his homeland of Saudi Arabia in 2007.
The deputy president of the asylum and immigration tribunal, Mark Ockelton, said their union "was not to be regarded as valid in English law", partly because they were both married to other people at the time.
Mr Ockelton said that he was "not satisfied" that the pair, who met in September 2006, had any intention of marrying or living together.
In rejecting Omar's request last year, British authorities in Egypt, where the couple were living, cited as one reason his "continuing loyalty" to his father and said his presence in Britain could cause "public concern".
"It seems to me that the presence in the United Kingdom of a person closely related to Osama bin Laden and expressing the views that the appellant does express would be likely to cause public disquiet and perhaps public disorder," he said.
Omar is the fourth of 11 children by his father's first wife and one of reportedly 19 fathered by the man who claimed responsibility for the September 11, 2001 attacks on the United States.
He has claimed not to have seen his father since 2000.
Zaina, formerly known as Jane Felix-Browne, is a Muslim who had been married at least five times before, the tribunal ruling said.
She was described as "in poor health, suffering from multiple sclerosis".