Johns, 46, spent the past three seasons as Memphis' offensive coordinator and quarterbacks coach. He made previous offensive coordinator stops at Western Michigan, Texas Tech and Indiana, where he worked from 2011 to 2016.
Memphis ranked in the top 10 in several offensive categories in 2019, and it finished 17th in passing and 22nd in total offense in 2020. Duke finished 102nd nationally in scoring (22.8 points per game) last season.
An Ohio native, Johns played wide receiver at Dayton. He spent much of his early career at Northwestern before earning his first co-coordinator role with Indiana in 2011.