Mouse Davis then moved on to take the head coaching position at Portland State University, where he coached from 1975 to 1980. While at Portland State from 1975 to 1980, and at each of his subsequent stops, he helped popularized the "Run & Shoot" offense.^{[citation needed]}

There he led the PSU football program to a 42-24 record over six seasons, averaged 38 points and nearly 500 yards of offense per game. PSU led the nation in scoring three times. The unique passing game made stars out of Davis’ two main quarterbacks, June Jones and Neil Lomax. In 1975, his quarterback, current University of Hawai'i head coach June Jones, threw for a Division II - record 3,518 yards. Davis' next quarterback, Lomax, set NCAA records of 13,220 yards and 106 touchdowns in 42 games. Under Davis' direction, Portland State set 20 NCAA Division II offensive records in addition to the Vikings being named the NCAA's all-time point producers in 1980, scoring 541 points in 11 games for 49.2 points per game, along with 434.9 yards passing and 504.3 yards of total offense per game.^{[citation needed]} After coaching at Portland State, Davis went on to coach at UC Berkeley.

The past three seasons, Davis served as an assistant coach for Jones with the University of Hawai’i. The Warriors employed the Run & Shoot offense and averaged 559.2 yards of total offense, 46.9 points and produced a 10-3 record in 2006. Hawai’i led the nation in passing offense (441.3), total offense, scoring offense and pass efficiency (185.95).^{[citation needed]} Then in February 2007, he returned to Portland State to serve as offensive coordinator for new PSU head coach Jerry Glanville's staff.Davis was an inaugural member of the Portland State Athletics Hall of Fame when he was inducted in 1997

Davis has been head coach of the now-defunct USFL's Denver Gold, the WLAF's New York/New Jersey Knights, and the Arena Football League's Detroit Fury. He was also an assistant coach with the NFL's Atlanta Falcons and Detroit Lions and with the Toronto Argonauts in the Canadian Football League