Wittenberg Director of Athletics Dr. Gary Williams announced the promotion.
"I am thrilled that Kelly has accepted our offer to lead our women's basketball program. She has been a loyal and hard-working staff member for both Wittenberg basketball and our athletic department over these past five years. I have the utmost confidence in her and in her ability to lead our program now and into the future."
Mahlum joined the Tigers' staff as an assistant to Sarah Jurewicz in 2011. Jurewicz is Wittenberg's Associate Director of Athletics and the program's all-time leading scorer.
"The relationships I have formed with current players in our program, the basketball alumnae, and the Wittenberg campus community is unmatched," said Mahlum in the release. "I am very thankful that I will get to continue adding to the tradition of success here at Wittenberg University."
After taking over as interim head coach in November 2016, Mahlum led the Tigers to a 10-16, 6-10 mark in the NCAC last season.
Before coming to Wittenberg, Mahlum was the head coach at Greensboro for two seasons from 1999 through 2001 and the head coach at Colorado College for seven seasons from 2001 through 2008. She has a career record of 93-154 in ten seasons, including last year at Wittenberg.