Colombia hosts nearly three million Venezuelan migrants, yet discrimination and distrust remain significant barriers to integration. Given the widespread use of WhatsApp, this intervention explores the platform's potential to improve migrant-host relations. In collaboration with Innovations for Poverty Action Colombia and El Barómetro, this study examines a WhatsApp video campaign – developed in an academic-NGO partnership and featuring positive economic, cultural, and social interactions between Venezuelans and Colombians – to enhance intergroup attitudes and socio-psychological integration. The randomized evaluation included 1,561 participants from 13 cities, randomly assigned to three groups: individuals receiving videos via WhatsApp, participants in WhatsApp co-viewing groups, or a comparison group viewing neutral, non-migration-related videos. The campaign led to positive changes in prejudice reduction and policy-relevant attitudes among Colombians, though the effects on Venezuelans’ attitudes were more limited. While participants expressed more positive norms about migrant-host relationships, they showed reluctance to share this content. To complement survey data and WhatsApp co-viewing group transcripts, we conducted one-on-one interviews with 20 participants to provide insights into their experiences and the potential mechanisms behind the observed effects. We also demonstrate the importance of measuring actual treatment uptake in video-based interventions. To this end, we tracked the time participants spent watching the videos and analyzed their engagement, including sharing behaviors. This study highlights the potential and limitations of digital campaigns and group-based messaging to foster social cohesion in migration contexts.