Marcus Daly was born in Long Branch, New Jersey on September 18, 1908. In 1930, he graduated from Georgetown University's School of Foreign Service; he was involved in higher education throughout his life. Daly received his Master's Degree in Political Science from Columbia University in 1949, studied International Law at The Hague Academy of International Law, and in 1961 was awarded the title of Professor Extraordinary from the Pontifical University of Colombia. In 1962, Daly was awarded honorary degrees from Monmouth College and St. Peter's College as a Doctor of Letters and a Doctor of Laws, respectively. Daly was married to the former Lucelle Burke of Plainfield, New Jersey. From 1931 to 1957, Daly was an insurance broker, an arbitrator in real estate and labor negotiations, and president of the Skelly Brewing Company.

Daly taught political science part-time at Fordham University from 1954-1958. In 1958, he was nominated by President Eisenhower to be the Director of the Intergovernmental Committee for European Migration (ICEM), an organization that was dedicated to the resettlement of European World War II refugees, as well as assisting in the emigration of people who wished to settle overseas. Elected unanimously to the post by the 28 member governments of ICEM, Daly was Director of the organization until 1961, and he oversaw the movement of at least one million migrants to such places as Australia, Brazil, Argentina, Chile, Colombia, the United States, and others. In 1961, Daly was awarded the Grand Croix de Merite of the Sovereign Military Order of Malta, their highest honor, for his work with ICEM. In 1962, Pope John XXIII named Marcus Daly a Knight Commander of the of the Order of St. Gregory the Great, the highest honor the papacy can bestow on a layman, for work in the international field and his dedication to human welfare.

After he stepped down as ICEM Director, Daly returned to his home in Lincroft, New Jersey where he played an active role in local and county politics. He also joined the faculty of St. Peter's College to lecture on political science and international law. From 1963 to 1968, Daly was an elected Freeholder for Monmouth County and held aspirations to be elected to Congress. In early 1967, Daly caused a major controversy because of his views on welfare, particularly his plan to turn over to the county prosecutor the names of unmarried welfare mothers who would be taken to court on charges of adultery and fornication. His controversial views caused quite a stir and he even appeared on the David Susskind Show on November 15, 1966.

Marcus Daly died on July 25, 1968.