ABSTRACT: Front-of-package (FOP) nutrition labels have been proposed as a strategy to help limit sugar-sweetened beverage (SSB) consumption among youth. However, few studies have examined the efficacy of FOP labels in youth across different countries. A between-group experiment was conducted to examine the impact of FOP labels (no-label control, Health Star Rating, 'High in' Octagon, Guideline Daily Amount (GDA), Traffic Light, or Nutri-Score) on perceived healthfulness of an SSB. The study was conducted online in November-December 2019 with 10,762 children aged 10-17 from six countries: Australia, Canada, Chile, Mexico, the United Kingdom, and the United States. A binary logistic regression model tested the impacts of FOP label condition, country, and sociodemographic characteristics on participants' likelihood of perceiving the SSB to be Unhealthy. Compared to the control condition, participants in each of the five FOP label conditions were significantly more likely to perceive the SSB as Unhealthy (p < 0.002). The 'High in' Octagon label had the greatest impact on perceived healthfulness across five out of six countries, whereas the GDA and Nutri-Score labels demonstrated the lowest impact across all six countries. The impact of FOP labels was consistent across sex, age, race/ethnicity, and perceived income adequacy. FOP labels can significantly reduce the perceived healthfulness of SSBs among youth across multiple countries. The current study adds to the evidence that 'high in' labels, which use intuitive symbols such as the octagon 'stop sign', are the most efficacious labels for helping consumers identify foods high in nutrients of concern, including SSBs.