Following his education, Friedsam returned to New York, and began to work for B. Altman & Co.. While working there, Friedsam developed a very close relationship with the president of the company, Benjamin Altman, and became manager. After Altman's death in 1913, Friedsam succeeded him as president of B. Altman & Co., as well as the Altman Foundation, a charitable establishment which received most of Altman's estate. Beyond all of this, Friedsam was named as heir and associate to Benjamin Altman and received his library, some of his paintings, and his home. The rest of his collection was given mainly to the Metropolitan Museum of Art and to the Brooklyn Museum. During World War I, Michael Friedsam served as Quartermaster General of the New York State Guard, where he gained the title "Colonel." Upon his death, April 6, 1931, Colonel Friedsam's fortune was left in trust, "for the care and education of the young and the care and comfort of the aged." And, although Friedsam was Jewish, this statement reflects some of the ideals held dear by the Order of Franciscans, found in Roman Catholicism. Hence in accordance with Colonel Michael Friedsam's request, the trustees of the Friedsam Foundation gave $125,000 for the construction of a new library building to St. Bonaventure University, a Roman Catholic and Franciscan institute, and later donated many pieces of Friedsam's personal art collection.