Theo Frei was born in Steinach on July 1, 1902 as the sixth of seven children of the merchant Bernhard Frei and his wife Rosa, née Löwenberger. The Frei family who came from Eichenhausen near Bad Neustadt had been living in Steinach at least since the middle of the 18^th century and had been butchers for generations. After the death of his father, Theo Frei’s mother moved to Bad Kissingen in 1912, presumably with the younger siblings.

The family's financial situation was obviously difficult. In 1928, Theo Frei, who was employed at the Ehrlich fashion house, asked the Jewish Community to waive his religious tax, as he also had to support his needy mother.

In April 1936, Theo Frei left Bad Kissingen and emigrated to New York. In November 1949, he married Frieda Frances Blucher, who was born in New York. He later lived in Miami-Dade in Florida, where his siblings Hugo and Bianca, married name Cohn, also lived. His brothers Hugo and Max had emigrated to the United States long before the Nazi era.

Theo Frei died in Miami-Dade, Florida, in April 1978 at the age of 75. His wife Frieda survived him by almost 30 years; she died there in November 2007 at the age of 95.