After five season in the Mets' minor league system, he made it to the big league club out of Spring training in . In the second game of the season against the Montreal Expos, Cornejo entered the game in the eighth inning with the Expos leading 5–2, and pitched the final two innings without giving up a run.
Cornejo spent five years progressing through the Mets' minor league ranks before being promoted to the major leagues during Spring training. In his second outing of the season against the Montreal Expos, he entered the game in the eighth inning with the Expos holding a 5–2 lead and successfully closed out the final two innings without allowing a run.