Robert McCorkill had willed his coin and artifact collection valued at $250,000 to the National Alliance, an American white supremacist organization, before he died in Saint John in 2004.
Isabelle Rose McCorkill, his estranged sister, challenged the will and won in a 2014 ruling.
In that ruling, Court of Queen's Bench Justice William Grant described the written materials of the National Alliance as "racist, white supremacist and hate-inspired."
"They are disgusting, repugnant and revolting," he said.
Such "hate propaganda" is both illegal in Canada and contrary to public policy, said Grant, voiding the will.
The National Alliance appealed the decision, but New Brunswick's top court dismissed the case on Thursday.
"Having regard to the application judge's comprehensive reasons and his determination that the bequest was void as against public policy, we can find no justification to interfere," the court said in its ruling.
"We are in substantial agreement with the essential features of the carefully considered reasons of the application judge."
The appeal court also awarded Isabelle Rose McCorkill, the Centre for Israel and Jewish Affairs and the New Brunswick government each $3,000.
McCorkill's collection includes Greek and Roman coins that are thousands of years old and an ancient Iranian sword, according to an appraiser's report from August 2010.
The University of Saskatchewan's Museum of Antiquities was lent a portion of his coin collection and put it on display for several years.
Around 2000, McCorkill left Saskatoon and moved to Ottawa, taking his coin collection with him.