Nyby was sent to South Vietnam as a photographer for the United States Air Force in 1963.
Nyby went on to direct multiple episodes of Emergency!, Battlestar Galactica, B. J. and the Bear, CHiPs, The A-Team, The Fall Guy, Hill Street Blues, Diagnosis: Murder and Walker, Texas Ranger.
Nyby also directed numerous Perry Mason television movies in the late 1980s and early 1990s.
Nyby's father, Christian Nyby, also a television director (as well as a film editor and director) directed multiple episodes of the original Perry Mason series.
Nyby considers his Hill Street Blues episodes as his favorites.