Formichi studied in Rome with Pio Di Pietro and in Firenze with Vincenzo Lombardi, and made his debut in December 1907 at the Teatro Olimpia in Bologna as Lescaut in Manon.
Soon, he was accepting a string of engagements to sing outside Italy, notably in Saint Petersburg (in 1912), Buenos Aires (in 1914), Paris (in 1922), Monte-Carlo, Vienna, and London (in 1924).
He went with a troupe of singers from La Scala on a tour of France in 1935, and later organized opera seasons in London.
Notable roles of his included Ashton, Rigoletto, di Luna, Amonasro, Iago, and some Wagner parts sung in Italian (Klingsor, for example).
Formichi possessed a big, rich-toned, important sounding voice which can be heard on the numerous acoustic and electrical recordings which he made during the peak of his career.