Haywards Heath town mayor Howard Mundin welcomed guests to the outdoor service, which started at 2pm at the War Memorial in Muster Green.
The event was organised by Haywards Heath Amnesty International with support from Haywards Heath Town Council.
School students, members of the Jewish community, faith groups and residents helped mark the Holocaust with prayers, readings and poetry.
Today is the 77th anniversary of the Soviet Red Army liberating Auschwitz, an infamous Nazi death camp, in 1945.
The victims of the Holocaust included six million Jewish people, hundreds of thousands of Roma, homosexuals, disabled people, Christian clergy, Russian prisoners of war and Polish civilians.
School students, members of the Jewish community, faith groups and residents helped mark the Holocaust with prayers, readings and poetry.