The second oldest of 14 children, Michael Ready was born in New Haven, Connecticut, to Michael T. and Mary A. (née Ellis) Ready. His parents were Irish immigrants who moved to the United States in the 1880s. In 1900, he and his family moved to Mansfield, Ohio, and later to Barberton.
He studied at St. Vincent Seminary in Latrobe, Pennsylvania, at St. Bernard Seminary in Rochester, New York, and at St. Mary Seminary in Cleveland.
Ready was ordained to the priesthood by Bishop John Farrelly on September 14, 1918. He then served as an assistant pastor, teacher, and director of the Society for the Propagation of the Faith in the Diocese of Cleveland. In 1931, he was named Assistant General Secretary of the National Catholic Welfare Conference, becoming its General Secretary in 1936. He was raised to the rank of Monsignor in 1934.
In 1939, Ready joined Bishops John Gannon and James Griffin in a visit to Mexico to confer with Archbishop Luis Martínez on a seminary founded in Las Vegas, New Mexico, to supply priests for the Mexican Church, since seminaries were at that time illegal in that country. He gave the benediction at the 1941 inauguration of President Franklin D. Roosevelt. Later that year, he met with Roosevelt after the latter made controversial remarks regarding the status of religious freedom in the Soviet Union.
In 1942, Ready declared that "the liberty and institutions" of the United States were threatened by the same "rampant totalitarian military forces which harass the Church and all that the Church has built," in an implicit reference to Japan. When Rev. Stanislaus Orlemanski returned in 1944 from a visit to Russia to see Joseph Stalin, who signed his written support for religious freedom, Ready described the priest's trip as "a political burlesque...staged and directed by capable Soviet agents," saying, "What we need from Stalin is his declaration of full religious freedom in Russia, not his signature." He also opposed conscription in favor of volunteer recruiting, and denounced the Spanish Loyalists in the Spanish Civil War.
On November 11, 1944, Ready was appointed the fifth Bishop of Columbus by Pope Pius XII. He received his episcopal consecration on the following December 14 from Archbishop Amleto Cicognani, with Archbishop John McNicholas, OP, and Bishop Edward Hoban serving as co-consecrators, at St. Matthew Cathedral in Washington, D.C. He was formally installed at St. Joseph's Cathedral on January 4, 1945.
One of Ready's first tasks was overseeing the erection of the Diocese of Steubenville from the eastern and southeastern portions of the Diocese of Columbus, as well as the consolidation of portions of the Archdiocese of Cincinnati into Columbus. He established the Catholic Welfare Bureau and appointed a Director of Charities for the diocese. Ready was among many critics of the Ohio State University Board of Trustees when the Board decided in 1951 that all speakers invited to the campus had to be cleared by President Howard L. Bevis in advance. During his tenure, he also served as chairman of the Bishops' Committee on Motion Pictures; he reported that Hollywood produced more films with "wholesome and moral qualities" in 1952.
Ready also organized the Holy Name Society, a Parent-Teacher Organization, the Council of Catholic Women, the Catholic Youth Council, and the St. Vincent de Paul Society in the diocese. He created 18 new parishes and oversaw the construction of nine elementary and five high schools. He founded two nursing homes, the diocesan Child Guidance Center, and the Catholic Student Center at Ohio State University. He worked with his fellow Ohio bishops to start the Ohio Catholic Welfare Conference.
Bishop Ready died from a cerebral hemorrhage, at age 64, and was buried at St. Joseph Cemetery in Columbus. Bishop Ready High School is named in his honor.