Post-pandemic, there is concern about the increase in mental health problems associated with grief due to COVID-19. Recent studies have identified positive outcomes that may have emerged in the face of adversity, which can lead to positive psychological changes, such as posttraumatic growth. The aim of the study was to evaluate the transnational measurement invariance of the 8-item Posttraumatic Growth Inventory-Short Form (PTGI-SF) in individuals who experienced the death of loved ones during the post-COVID-19 period. A total of 1,820 individuals were recruited from four South American countries (Ecuador, Colombia, Peru and Bolivia) using non-probabilistic snowball sampling. The highest average age of participants was observed in Colombia (M = 35.8; SD = 12.5 years), while the lowest was recorded in Bolivia (M = 28.4; SD = 10.5 years). Similarly, a higher proportion of women (>57%) was found across all countries. Confirmatory Factor Analysis (CFA) and multigroup Confirmatory Factor Analysis (CFA) methods were used. The results indicated that a model for measuring posttraumatic growth across the five countries was supported, encompassing four factors: relating to others, appreciation of life and opportunities, personal strength, and spiritual change. Furthermore, the four-factor structure showed sufficient strict invariance across the five countries. Similarly, the PTGI-SF-8 items demonstrated adequate discrimination and difficulty parameters. The findings provide initial evidence to consider the PTGI-SF-8 as a psychometric instrument for assessing posttraumatic growth.