In 1927 she entered the Berlin State Academy of Music and in 1929 graduated from its master class in conducting, the first American to do so. During that period she was also a pupil of Karl Muck, conductor of the Hamburg Philharmonic Orchestra, with whom she studied for a further three years after graduation. Following her debut as a professional conductor with the Berlin Philharmonic Orchestra in February 1930, Brico worked with the San Francisco Symphony and the Hamburg Philharmonic winning plaudits from critics and the public. Appearances as guest conductor of the Musicians' Symphony Orchestra in Detroit, Washington, D.C. and other sites soon followed. In 1934 she was appointed conductor of the newly founded Women's Symphony Orchestra which, in January 1939 (following the admission of men), became the Brico Symphony Orchestra.
Brico settled in Denver, Colorado from 1942 onwards. Here she founded a Bach Society and the Women's String Ensemble. She also conducted the Denver Businessmen's Orchestra, which in 1968 became the Brico Symphony Orchestra, and in 1948 became conductor of the Denver Community Symphony (later the Denver Symphony Orchestra). She taught piano to such students as Judy Collins and Donald Loach. Brico continued to appear as guest conductor with orchestras around the world, including the Japan Women's Symphony.
A documentary film about Brico's life, entitled Antonia: A Portrait of a Woman, by director Jill Godmilow, with help from Brico's former student, Judy Collins, appeared in 1974. Brico died in 1989 after a long illness at the age of 87. She had lived at the Bella Vita Towers, a nursing home in Denver since 1988.