This study aims to examine what makes the image content of fashion brands successful on Instagram, while comparing between luxury and fast fashion brands. A quantitative analysis of a massive collection of fashion photos posted by notable luxury and fast fashion brands was therefore conducted to identify specific patterns in these images based on four important visual content variables: the use of a brand name, brand logo, text, and hashtag. This study also examined how user engagement levels vary depending on each visual content variable. This study made several interesting findings: (1) luxury brand images with logos and brand names had higher user engagement whereas fast fashion brand images did not show this same trend; (2) the size of the brand name and logo in an image was negatively related to the user engagement or had no effect, regardless of the brand category; and (3) the use of embedded text within an image positively influenced user engagement for luxury brands whereas it negatively influenced user engagement for fast fashion brands.