She performed in George White's Scandals with Joan Crawford and Anita Page for a series of MGM romantic dramas Our Dancing Daughters (1928) and Our Blushing Brides (1930). Sebastian also appeared in (1929) Spite Marriage, where she was cast opposite her lover in real life Buster Keaton.
Sebastian went into semi-retirement in the mid-1930s after marrying Hopalong Cassidy star William Boyd. They married in Las Vegas, Nevada. After their divorce in (1935), Sebastian made comeback in much smaller roles.