The job at Douglass came open last month when Terry Long left the school to become the head coach at Mustang.
Ingersoll had been selected for the position by a search committee made up primarily of people connected to Douglass High School, from administrators to students.
Ingersoll coached Douglass to three state championships in the 1980s. He led Northeast to titles in 2002 and 2004 before stepping down. He worked as OKCPS athletic director from 2008-11. He was inducted into the Oklahoma Basketball Coaches Association Hall of Fame in 2006.