Police say the department received a tip last week that Morris stole an undisclosed amount of money from another employee at the high school.
Mabton police arrested Morris during school hours Thursday and questioned him about the theft.
Investigators say once Morris was in custody, he took full responsibility and admitted to stealing the money.
Morris was charged with third degree theft in a Sunnyside court and was released on his own recognizance.
Mabton police say they were able to recover a small amount of the money.
Morris is a language arts teacher and has worked in the Mabton School District for seven years.
Mabton Superintendent Minerva Morales tells KIMA that Morris has been placed on paid administrative leave pending an investigation from the school district.