Social-Emotional Learning (SEL) is essential for teacher effectiveness, yet its incorporation into online English Language Teaching (ELT) teacher training—particularly via a gender-responsive lens—needs further exploration. This study examined the way SEL can be incorporated in a mixed-methods, quasi-experimental online ELT teacher training program lasting for 10 weeks, which embedded reflection and discussion with video-based tasks every week. Sixty pre-service teachers (30 identifying as female, 30 as male) took part in the study. Data were gathered from pre- and post-intervention SEL surveys, online discussion transcripts, and semi-structured interviews. Overall, SEL competencies had a significant increase (e.g., t(59)=7.84, p<.001). Females demonstrated higher gains in empathy and interpersonal communication, whereas males indicated greater gains in self-regulation. Effect size analyses indicated that gender explained 8–10% of the variance in self-regulation, empathy, and interpersonal communication—medium effects that highlight practically significant differences in the way male and female trainees gained from the program. Qualitative findings showed that differences by gender in communication, emotional expression, and responsiveness to feedback formed online engagement. Results suggest that integrating SEL explicitly in ELT teacher training promoted SEL competencies pertinent to professional practice. Results pinpoint the value of incorporating SEL in online training settings and adapting activities in ways that are responsive to observed gender-based engagement differences within cohorts.