As a general rule, each undergraduate chapter elects a female associated with the chapter as the chapter sweetheart. At each Grand Chapter, the fraternity chooses a Sweetheart from one chapter to be the International Sweetheart of Sigma Chi for two years. The International Sweetheart Award is presented based on personality, character, campus involvement, Sigma Chi activities, general accomplishments, poise, and grace. Each nominee must be the sweetheart of an undergraduate chapter for the year nominated and a student at the nominating chapter's university.  The first International Sweetheart of Sigma Chi was Barbara Tanner, a sister of Kappa Alpha Theta. The current Sigma Chi International Sweetheart is Rachel Berkey from Harvard College.

Some notable Sigma Chi Sweethearts include Judy Garland and Faye Dunaway.

The current Sweethearts at the Iota Upsilon Chapter are Annie Thorne '11 and Phoenix Porcelli '11.