The move reunites Musgrave with head coach Jack Del Rio. Each held the same position with the Jacksonville Jaguars in 2003-04.
Eagles quarterbacks combined to throw for 4,356 yards, 27 touchdowns and 21 interceptions this season, with starter Nick Foles giving way to Mark Sanchez in November after Foles injured his collarbone.
The Raiders, meanwhile, finished last in the NFL in total offense in 2014, averaging 282.2 yards per game. Rookie quarterback Derek Carr, Oakland's second-round pick in last year's NFL draft, threw for 3,270 yards, 21 touchdowns and 12 interceptions.
Before joining the Eagles in 2014, Musgrave spent the previous three seasons as the offensive coordinator for the Minnesota Vikings. He's also worked as an assistant for the Atlanta Falcons, Washington Redskins and Carolina Panthers, and spent one year as the Raiders' quarterbacks coach in 1997.
The Raiders fired head coach Dennis Allen in September, with Tony Sparano taking over as interim coach the rest of the season. Del Rio was hired last week after spending the last three years as the defensive coordinator for the Denver Broncos. He had previously served as the Jaguars' head coach from 2003-11.
This marks the second straight offseason the Eagles' quarterbacks coach has left to become an offensive coordinator. Bill Lazor left to become the OC for the Miami Dolphins last year.
The Raiders went 3-13 last season and missed the playoffs for the 12th consecutive year.
- Ben Estes