Apples (Malus domestica L.) are among the most widely consumed fruits and are rich in dietary fiber and polyphenols. Apple polyphenols are diverse, encompassing a wide array of chemical classes, including hydroxycinnamic acids, phloretin glycosides, quercetin glycosides, flavan-3-ols, and procyanidins. Flavan-3-ols and procyanidins account for approximately 70% of the total polyphenol content. The polyphenol content of apples is influenced by various factors, including cultivar, geographical origin, and storage conditions. Apple polyphenols have been shown to possess antioxidant, anti-inflammatory, and cardiometabolic benefits, including the improvement of glucose and lipid metabolism and the reduction of cardiovascular risk. Recent research highlights the role of the gut microbiota in mediating polyphenol effects, suggesting potential benefits for obesity, diabetes, and metabolic syndrome. Furthermore, most polyphenols and their metabolites, which are metabolized by the gut microbiome, have been shown to enhance intestinal barrier function and demonstrate anti-inflammatory and antioxidative properties. However, further research is required to elucidate the mechanisms underlying these functionalities of apple polyphenols.