Surprised Brookmans Park resident Janis Sharp said she had no idea who had nominated her for the award from human rights watchdog Liberty, but said she was “honoured”.
Ms Sharp, 62, told the WHT: “I just think it’s incredible and it’s an honour.
“This will help me highlight Gary’s case and it will help me highlight the extradition treaty, which means that anyone can be sent away without evidence.
“And the fact that it’s Liberty and human rights is great.”
Last week a review of the 2003 extradition treaty, which was conceived in the aftermath of the 9/11 attacks, found it to be fair, dealing Ms Sharp’s campaign a major blow.
The probe, led by the former Court of Appeal judge Sir Scott Baker, said the treaty “does not operate in an unbalanced manner”.
Sir Scott’s report found: “There is no practical difference between the information submitted to and from the United States.”
Ms Sharp has been nominated for her tireless battle to halt her son being taken to America to answer charges of hacking into US government computer systems, including that of the Pentagon.
Mr McKinnon, 45, who has Asperger’s Syndrome, was said to have been looking for evidence of UFOs.
The winners of Liberty’s annual awards will be announced next month.