Doeren comes to North Carolina State from Northern Illinois, which he helped lead to a second straight MAC championship Friday.
Doeren compiled a 23-4 record (17-1 in the MAC) in two years of guiding the Huskies.
"I am honored and excited to join the Wolfpack," he said. "N.C. State has world-class facilities and fans that are second to none."
O'Brien was fired after the Wolf Pack went 7-5 this season with a 4-4 mark in ACC games.