The Senate is the largest branch within the Western Student Association. It is made up of senators representing registered student organizations and academic colleges at Western Michigan University. Each organization that is registered through Student Activities and Leadership Programs receive one senator position. Each academic college receives one senator position and an additional position for every 500 students in that respective college. The Senate is responsible for addressing all legislation brought before it. The legislation acts as resolutions to the administration.

The Senate itself is broken down into eight committees: Academic Affairs, Campus Sustainability, Community Involvement, Diversity Guidance, Political Affairs, Public Relations, Student Affairs, and University Pride. The Western Student Associations Senate meetings occur every Wednesday at 4pm.