While still working on his MA at Brigham Young University, Gillespie began teaching art at Springville Junior High. After teaching there for two years he transferred to Maple Mountain High in 2009. As an high school art teacher, Gillespie believes that "a serious study of art can not only develop craftsmanship, patience and skills related to individual media and certain materials, but it can also engender divergent and critical thinking, observation skills and creative problem solving" which are all necessary for his students' future success in life.
In 2011, Jethro Gillespie was chosen to participate in Art21 Educators, a program designed to introduce contemporary art into art education for grades K-12.
Still teaching at Maple Mountain High, Gillespie was named the Utah High School Educator of the Year in 2012.