The New York-based collective of film historians, student and academics also gave Amy, Asif Kapadia's film about Amy Winehouse, its best documentary prize.
Ridley Scott was named best director for The Martian, which also picked up prizes for lead actor Matt Damon and Drew Goddard's adapted screenplay.
Sylvester Stallone won best supporting actor for Rocky spin-off Creed.
National Board of Review president Annie Schulhof said: "2015 has been a banner year for popular cinema.
"We are thrilled to be awarding [Mad Max director] George Miller and Ridley Scott, two iconic film-makers at the top of their game, while also celebrating the next generation of talent," she added.
Mad Max, starring Tom Hardy and Charlize Theron, was warmly reviewed but will be seen by some as an unusual choice for the board's best film award.
So far it has been considered unlikely to figure in the forthcoming awards season, with most of the attention geared towards films such as independent dramas Spotlight, Brooklyn and Carol.
Earlier this week, Spotlight was the star feature at the Gotham Awards for independent film in New York, where it won best picture, screenplay and the jury award for its ensemble cast.
The Thomas McCarthy-directed drama centres around the true story of the Boston Globe's investigative "Spotlight" team as they endeavour to undercover the truth behind allegations of sexual abuse among Roman Catholic priests in Massachusetts.
Other National Board of Review honourees included Brie Larson, the star of Room. The best actress win will bolster her status as a likely Oscar candidate for her role as an imprisoned young woman.
Quentin Tarantino, meanwhile, picked up the original screenplay award for his new western The Hateful Eight, which also saw Jennifer Jason Leigh named best supporting actress.
The 2015 William K Everson Film History award winner was Cecilia De Mille Presley, the granddaughter of legendary director Cecil B DeMille and a campaigner of film preservation.
The winners of the awards are selected by more than 100 New York film fans.  History has shown they have a mixed success rate in predicting Oscars glory.
Last year, they named JC Chandor's A Most Violent Year as best picture and its star Oscar Isaac as best actor, with his co-star Jessica Chastain picking up the best supporting actress award. However, the film was ultimately overlooked at the Academy Awards.
The winners of this year's awards will pick up their statues at a celebratory dinner on 5 January.

Sum: Futuristic sequel Mad Max: Fury Road has been named film of the year by the influential National Board of Review.


The consumer group said almost a third (28%) of more than 1,000 UK 18- and 19-year-olds university applicants surveyed said they wished they had chosen different subjects.
And 41% wished they had considered which subjects would be of most use.
The Russell Group of selective universities said clear information on subject choice was crucial.
The research, carried out by Youth Sight, in January, also found only about half of the university applicants felt well enough informed at school about how the subjects they had studied could affect their choice of degree and university.
Some degrees require specific A-levels of equivalents and some universities do not consider certain subjects challenging enough, warns Which?
However, only 41% of the teenagers surveyed were aware of this.
And 30% complained the advice they had received had failed to warn them of the impact choices made at 16 could have on their future prospects.
Russell Group director general Wendy Piatt said it was "really important for all young people, especially those whose parents didn't go to university, to have clear information about how the subjects that they choose to study in the sixth form or at college can affect their options at university and their chances in life".
In 2011, the group published its Informed Choices guide to the most useful school subjects for students aiming at one of its 24 universities.
The guide suggests 16-year-olds should study two of the following "facilitating" subjects to keep a wide range of options open:
Which? University has also launched an Explorer tool to help 16-year-olds and their teachers to explore their options.
"While certain A-levels might suggest a particular degree path, our tool shows there are usually alternative options students can take," said Which? campaigns director Alex Neill.
And student Dan French, who is applying to Salford University, said he wished it had been available when he had been 16.

Sum:
Too many university applicants realise too late they picked the wrong school subjects at 16, says Which?