The purpose of this review paper is to present the application of herding behavior in online buying. The simplest description of herding behavior is the imitation of others in making decisions. Online buying platforms have facilitated observing others' buying behavior, thereby increasing possibilities of social influence on our information search, evaluation, and buying. The concept of herding is multi-disciplinary; however, the literature review on herding behavior is mainly grounded in economics and finance. There is little understanding of herding behavior in marketing literature. Therefore, this study covers herding behavior literature through high-quality research papers published from 2000 to 2020 in journals indexed in the social science citation index, science citation index expanded, and emerging source citation index. This paper discusses the conceptualization of herding in online buying, herding situations, information-processing view of herding, measuring herding effect, herding models and theories, and areas for future research to enrich herding literature in online buying. This paper proposes a herding model (HCMMD) based on the stimulus-organism-response (SOR) theory to study herding behavior. Keywords: Consumer Herding Behavior, Herding Literature Review, Herding Models, Online Buying, Stimulus-Organism-Response (SOR) Theory.