Alexander, 27, was selected No. 8 in the 2008 draft by the Milwaukee Bucks.
The 6-foot-8, 230-pound forward averaged 4.2 points and 1.8 rebounds over two NBA seasons before the Bucks declined to pick up his third-year option. He has since played in the D-League and in Russia.
Over three seasons at West Virginia, Alexander posted averages of 12.1 points and 4.8 rebounds.
The Nuggets went 36-46 and missed the playoffs last season.
- Chris Johnson