In his first year as Denver's head coach, he led the 1977 Broncos to Super Bowl XII, where they lost to the Dallas Cowboys.
Miller was also the head coach of the Denver Gold of the United States Football League (USFL) for one season, in 1983.
Miller was named head coach of the Denver Broncos on February 1, 1977, replacing John Ralston, who resigned the previous day, after his best season.
[1][2][3][4] Miller took a team led by linebackers Randy Gradishar, Bob Swenson, and Tom Jackson, cornerbacks Louis Wright and Bernard Jackson, safety Billy Thompson, and defensive end Lyle Alzado— mainstays of the Orange Crush Defense— and veteran quarterback Craig Morton (acquired via trade with the New York Giants) to a 12–2 regular season record and an AFC championship.
After posting an 8–8 record in 1980 and failing to return to the AFC playoffs, Miller was fired[5] by new owner Edgar Kaiser in March 1981, and was succeeded by Dan Reeves, previously the Dallas Cowboys' offensive coordinator and a former NFL running back.