'12 Years A Slave', an intimate and disturbing portrayal of slavery in America, won the best picture award while its lead star Chiwetel Ejiofor, 36, was named the best actor for his portrayal of a free man sold into slavery.
"There are 21 million people in slavery now as we sit here. I just hope that 150 years from now our ambivalence will not allow another film-maker to make this film," McQueen said.
However, McQueen, 44, lost the best director trophy to 'Gravity' helmer Cuaron in the Sunday night awards gala.
The Mexican director, 52, who has called London his home for 13 years, said his accent may be different but he considered himself a part of British film industry.
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"I guess I make a very good case for curbing immigration," Cuaron joked, adding 'Gravity' would not have been possible without its leading lady Sandra Bullock.
The award for leading actress went to Cate Blanchett for her portrayal of socialite on the verge of a meltdown after she loses her high-flying lifestyle in 'Blue Jasmine'.
Blanchett, 44, did not mention film's director Woody Allen, who is facing allegation of molesting his adopted daughter, a case that has come to haunt him after two decades.
Blanchett paid tribute to "the late great Philip Seymour Hoffman", who died of a suspected drug overdose recently.
"You raised the bar so very high... So, Phil, this is for you, you bastard. I hope you are proud," she said.
Newcomer Barkhad Abdi was named best supporting actor for his portrayal of a Somali pirate in 'Captain Phillips'.