The women launched their campaign following the sinking of three ships in 1968 with the loss of 58 lives.
They lobbied the government and eventually forced the introduction new safety measures, including all ships having a full-time radio operator.
The ceremony was performed by the city's Lord Mayor Mary Glew.
Councillor Glew described the four women, Lillian Bilocca, Christine Jensen MBE , Mary Denness and Yvonne Blenkinsop, as "truly inspirational".
"The women's campaign saved millions of lives across the world in the fishing industry and it is right and fitting that they are honoured," said Ms Glew.
The four, who lived in the Hull fishing community of Hessle Road, gathered a 10,000 signature petition calling for reform.
Lillian Bilocca led a delegation to Parliament and eventually met with the then prime minister Harold Wilson.
The ceremony takes place on what would have been Ms Bilocca's 86th birthday. She died in 1988.
The two surviving campaigners, Mary Denness and Yvonne Blenkinsop, were present at the unveiling.
Christine Jensen died in 2001.
Plaques have been unveiled in Hull Maritime Museum to mark the battle by four women to improve safety conditions on board North Sea trawlers.