As the population of individuals with diabetes and obesity continues to grow, the utilization of resistant starch (RS) in low-glycemic index and low-caloric foods has become more popular. Hydroxypropyl starch (HPS) is a chemically modified starch developed decades ago and has been widely used in both food and non-food applications. HPS with high degrees of substitution has substantial amounts of RS. Meanwhile, it also provides superior textural functionality in foods when comparing with other RSs, such as cross-linked starch and high-amylose starch. Moreover, long-term consumption of HPS has demonstrated certain health benefits, including increased energy expenditure, obesity prevention, and reductions in glycemic response, insulin resistance, and plasma cholesterol levels. Despite these benefits, the mechanism behind the enzymatic resistance of HPS, however, remains unclear. Therefore, the objective of this work is to provide a comprehensive review of the formation of resistant starch in HPS. Through this review, we aim to contribute to a better understanding of HPS for its applications in the food industry.