Northwest Missouri State announced Wednesday the renowned ex-coach will begin his new role in mid-April.
Tjeerdsma, now 66, won three NCAA Division II national championships at Northwest Missouri State before announcing his retirement in December 2010.
He retired with a record of 183-32 over 17 seasons. His Bearcats won 12 MIAA championships and also played in four other NCAA championship games.
As AD he succeeds Wren Baker, who resigned earlier this month for a job at the University of Memphis.
Tjeerdsma said in a news release that Northwest Missouri has a "rich and outstanding tradition." He vowed to ensure the athletic program continues to "thrive and improve."