Childhood sexual abuse (CSA) is a major social problem with various negative outcomes for a person’s life, such as dissociation. Previous research has shown that insecure attachment styles, especially disorganized attachment, play a role in mediating the effect of childhood sexual abuse on dissociation. However, most of these studies have not considered several abuse characteristics, such as relationship to the perpetrator, to play a role in determining the effect of childhood sexual abuse on outcomes such as dissociation. Our study borrows from betrayal trauma theory that states the effects of a traumatic event vary considerably based on one’s relationship to perpetrator, with more severe consequences for those traumatized at the hands of someone close to them. Therefore, this study aimed to analyze the mediating role of attachment styles on the relationship between child sexual abuse and dissociation in terms of the relationship to the perpetrator. A sample of 258 adult men and women between the ages of 18 to 55 years was selected via convenience sampling. Individuals completed questions from Childhood Trauma Questionnaire, Dissociative Experiences Scale, and Relationship Scales Questionnaire. Based on their relationship to perpetrators, participants were divided into two groups. Two mediation analyses were performed in each group to evaluate the mediating effects of attachment styles on the association between childhood sexual abuse and dissociation. Mediation analyses showed that fearful avoidant (disorganized) attachment partially mediated the relationship between CSA and dissociation (indirect = 0.10, 95% CI [0.0284–0.1833]) only in participants whose perpetrator was someone within their family. Results are discussed in terms of the role of victim-perpetrator relationship and attachment styles in pathways to dissociation.