Cornejo grew up in San Bernardino, California, where he attended Jurupa Valley High School.
[1] As a sophomore in 2002, he transferred to the University of Oklahoma, Cornejo batted .325 with a .411 SLG, 17 doubles, and 31 RBIs.
Cornejo began his coaching career in 2011, as an assistant for the UC Riverside Highlanders.
[5] He left the Gauchos following the 2018 season to join the staff of the San Jose State Spartans.
[6] He would join Dave Serrano's staff on the Cal State Northridge Matadors for the 2020 season.