In the 1960s, Hier served as assistant rabbi and, in 1964, became rabbi of Congregation Schara Tzedeck in Vancouver, British Columbia. In 1977, following a visit to Holocaust sites in Europe, Hier came to Los Angeles to create the Simon Wiesenthal Center. Under his leadership, the center has become one of the foremost Jewish human rights agencies in the world, with a constituency of more than 400,000 families. The center maintains offices throughout the United States, and in Canada, Europe, Israel and Argentina. Hier is the recipient of two Academy Awards - in 1997, as co-producer of The Long Way Home, which offers new insights into the critical post World War II period between 1945 and 1948 and the suffering of the tens of thousands of refugees who survived the Holocaust, and in 1981 as co-producer and co-writer for Genocide, a documentary on the Holocaust. In 1990, he wrote and co-produced the award-winning Echoes That Remain, a documentary on pre-World War II European Jewish life, and in 1994, Hier produced and co-wrote, Liberation, the first production of Moriah Films. Under Hier's direction, the Wiesenthal Center has served as consultant to Steven Spielberg's epic Schindler's List, and ABC Television's miniseries adaptation of Herman Wouk's novel, War and Remembrance. He is the recipient of an honorary degree and, in 1993 was made a Chevalier in the Ordre National du Mérite by French PresidentFrançois Mitterrand. Newsweek describes Hier as the following, "Hier is one phone call away from almost every world leader, journalist and Hollywood studio head. He is the dean and founder of the Simon Wiesenthal Center, the Museum of Tolerance and Moriah Films." In 2007 and 2008 Marvin Hier was named the most influential rabbi in America by Newsweek. Hier founded the Yeshiva University High Schools of Los Angeles and was the dean of the school until the 2006-2007 school year. President George W. Bush appointed Hier to serve on the honorary delegation to accompany him to Jerusalem for the celebration of the 60th anniversary of the State of Israel in May 2008. In 2009, he criticized Vatican cardinal Renato Martino over his comment that the Gaza Strip was a "big concentration camp". He later criticized the lifting of the excommunication of bishop Richard Williamson, a member of the Society of Saint Pius X. A $100 million Museum of Tolerance and Human Dignity, a project of the Simon Wiesenthal Center in Los Angeles run by Marvin Hier, is set to be built in Jerusalem, Israel. In 2013, The Forward called Hier the "most overpaid" executive of a Jewish non-profit. Hier's family received nearly $1.3 million in 2012 from the Simon Weisenthal Center. He gave an invocation at the inauguration of Donald Trump. He has participated in fundraising events for Trump's 2020 reelection. He was "the first Orthodox rabbi ever to give a benediction at an American president's inauguration". He cited psalm 137: "By the rivers of Babylon... We wept as we remembered Zion. If I forget thee, Oh Jerusalem, may my right hand forget its skill." Eleven days later, fourteen Jewish community centers across ten states were targeted with bomb threats; Hier had no public statement on the threats. In 2019 Marvin attended the Peace to Prosperity conference in Bahrain. During the June 25–26 economic conference in Manama, Hier praised the government of Bahrain saying, “If every Arab country were to be like Bahrain, the Messiah would arrive!”
