Background Self‐compassion may protect individuals experiencing poor body image and associated maladaptive outcomes. The purpose of the study was to examine within‐person associations (whilst controlling for between‐person differences) between appearance‐related self‐compassion, appearance‐related threats (operationalised as upward appearance comparisons), and body image‐related variables, namely, social physique anxiety, drive for thinness, and body dissatisfaction. Methods A diary methodology was used whereby young women (n = 126; Mage = 21.26) responded to brief online surveys three times per day (11am, 3pm, and 7pm) every second day for one week (i.e. a total of 12 measurement points). Results Results of mixed linear modeling revealed that both state appearance‐related upward comparisons and self‐compassion independently predicted all three outcomes in a positive and negative fashion, respectively. No significant interaction effects between state appearance‐related upward comparisons and self‐compassion were found. Conclusions The results suggested that appearance‐based self‐compassion was important, not just when there was a potential threat to body image via upward appearance comparisons. The findings highlight the importance of fostering self‐compassion on a daily level.