Mother’s emotions provide a key context for children’s emotional development. Children interpret these emotions through the lens of their relationship, with empathy, guilt, and reparative behaviors toward mothers emerging early in life. Over time, these interactions are thought to support regulated empathic responses, though far less is known about children’s responses to mothers’ emotions beyond early childhood, especially neural activity and responses to positive emotions. Middle childhood is a period in which children’s empathic responses become more differentiated and shaped by relational meaning and personal relevance, yet this developmental window remains understudied. The current study used an fMRI design to examine blood-oxygen-level-dependent (BOLD) activity associated with children’s empathic responses to their mothers’ emotions, capturing variation by relational context (mother vs. stranger), emotional valence (happiness vs. sadness), and personal responsibility (child-related vs. child-unrelated). Children (N = 33) viewed images of their mothers and a stranger expressing happiness or sadness while hearing audio recordings describing the cause of the emotion that was related or unrelated to their behavior. BOLD activity was examined in regions engaged during affect sharing, mentalizing, forming an empathic understanding, self-referential processing, emotion regulation, and reward processing. Across all emotional conditions, the mPFC showed consistently greater BOLD activity than a non‑emotional control, suggesting children process others’ emotions through a broadly self‑referential lens. The amygdala, dmPFC, and vmPFC showed greater activity when children viewed their mother’s sadness (vs. control), and the amygdala responded more strongly to maternal than stranger sadness, highlighting the salience of caregiver distress. Personal responsibility further modulated BOLD activity: the dmPFC had greater activity during child-related than child-unrelated maternal sadness, and both dmPFC and mPFC had greater activity for child-related maternal sadness than happiness, reflecting greater mentalizing and self-referential processing when children perceived themselves as responsible for their mother’s distress. Other regions showed minimal differentiation across conditions. Overall, children’s BOLD activity when viewing their mother’s emotions in middle childhood was selective, context‑sensitive, and varied by emotional valence, relational context, and personal responsibility, with a central role of self-referential processing. These results provide insight into how children integrate relational and causal information when interpreting their mothers’ emotions.