Eric Terwilliger was born in 1954 in Bloomington, Indiana, and first showed an inclination toward playing the horn at the tender age of three. At ten years of age, he made his first public appearance and started his formal study of horn at 18 with Philip Farkas at Indiana University in Bloomington. As early as 1975, he received a performer's certificate and then continued his studies with Michael Hältzel in Detmold and at the Mozarteum in Salzburg. That same year, he became principal horn player at the State Theatre in Kassel, a position he held until 1976 prior to moving on to the same post with the Munich Philharmonic.

Since September 1, 2007, he serves as principal horn player in the Symphonieorchester des Bayerischen Rundfunks. After winning prizes in Geneva in 1976 and Liège in 1981, he made a number of solo appearances with leading orchestras world-wide. In 1994 he was appointed to a professorship at the Johannes Gutenberg University in Mainz, continuing on to the Richard Strauss Conservatory in Munich in 1998. Since 2006 he has been active as a guest professor at the Conservatorio Superior de Aragón in Zaragoza, Spain.