This study examined whether mothers with schizophrenia spectrum disorder (SZSD) or mothers with bipolar disorder express less warmth, and more criticism compared to controls and whether mothers’ expressed warmth and criticism are associated with child self-esteem and mental health outcomes. Sixty mothers with SZSD, 60 mothers with bipolar disorder, and 60 control mothers, and their 7-year-old children were included from The Danish High Risk and Resilience Study VIA 7. Expressed warmth and criticism were evaluated by coding Five Minute Speech Samples using the Family Affective Attitudes Rating Scale. Child self-esteem was assessed with the “I Think I Am.” Child global functioning was assessed with the Children’s Global Assessment Scale, mental health with the Child Behavior Checklist School-age version, and KIDSCREEN-10 captured quality of life. Results showed that mothers with SZSD and mothers with bipolar disorder did not differ from controls on expressed warmth or criticism. Across groups, expressed criticism showed robust associations with poorer child mental health outcomes also when controlling for child sex and maternal functioning. Diagnostic status did not affect maternal expressed warmth or criticism toward their child. However, because more expressed criticism can be associated with adverse child outcomes, interventions promoting more positive interpretations may aid child mental health.