The district announced the hire Monday.
Steggall replaces Dr. Jaime Dial, who resigned from the district to become the Director of Secondary Education for the Park Hill School District.
Her new title comes with a $108,334 salary.
Steggall has been the principal at Truman Middle School since 2010.
She has also served as assistant principal at Truman and was a business teacher at Central High School.
"Sandy Steggall has a proven record of excellence with the St. Joseph School District. She brings a wealth of knowledge to this position and is well respected in the district and community," said Dr. Fred Czerwonka, Superintendent of Schools. "She has extensive experience in a variety of areas which will serve our students, administrative team, and teaching and support staff in a great way."
The district also announced a replacement for Mrs. Dial's husband, who also resigned as the assistant principal at Truman Middle School.
Ashly Bliss will take over for Mike Dial, who accepted a position as assistant principal at Oak Park High School.
Bliss worked as a special education teacher and 8th grade math teacher at Truman.
Bliss will make $73,980.
The district will begin the search for a new principal at Truman this week.