The Associated Student Body (ASB) government structure consists of a President and three executives elected in a school-wide election as well as a President and executives representing each of the four classes at Prep.

The ASB represents the student body at the school and the students serving on the ASB are the top formally elected students at Prep. Members of the ASB attend a leadership camp during the summer and participate in an annual Ignatian leadership retreat rotating through the 4 Northwest Ignatian high schools.

Seattle Prep's ASB organizes the Back to School Dance, Homecoming Week, TOLO, Glow Dance, and Prom. One of the most exciting weeks of the year at Seattle Prep is Olympic Week--a week in which the entire school participates in competitions and activities-- is entirely organized by the students in the ASB.