Cardinal Ritter Prep opened its doors on September 6, 1979. Named for Cardinal Joseph Ritter, Archbishop of St. Louis in the mid-1900s, Cardinal Ritter Prep honors its namesake as one of the most prominent and influential church and civic leaders of the century.
 
In 1977- 1978, a community representative task force was established by the Board of Catholic Education of the St. Louis Archdiocese to study the future existence of a Catholic school in the old Labouré location at in North St. Louis. Arrangements to establish Cardinal Ritter College Prep High School as a co-educational college preparatory high school began in August 1979.