This article discusses marital suffering, as portrayed by Sylvia Plath from a feminist viewpoint, and claims that her delineation of marital afflictions is a tool of protest against patriarchal oppression. In a convention-ridden patriarchal society, a woman usually cannot express her voice and remains suffocated by her personal agony and ache. However, Plath tries to break the conventions in her poetry, by representing the unjust institution of patriarchal marriage, which treats women as commodities. Many critics have noted that Plath’s marital sufferings are responsible for her suicidal death, which is a means of protest against, and resistance to, patriarchy. Since her poetry represents both her psycho-social suffering and her fight against the margins set by patriarchal society, one may consider her poetry to be a weapon of setting her “self,” as well as other women’s, free from male-dominated psychological imprisonment. The article explores how Plath’s poetic persona emerges as the Phoenix, the libertarian spirit, by deliberately exposing her marital sufferings, psycho-sexual torture, husband’s infidelity, and the ultimate death resulting from conjugal unhappiness, which is interpreted as a protest against all kinds of patriarchal discriminations.