To assist in understanding the progress of polysaccharide biopolymers in EOR, this review collects and summarizes the available data for the first time and thoroughly discusses the structure–property–EOR performance relationship from flask to field scale application. Attentions were given to xanthan, scleroglucan, hydroxyethylcellulose (HEC), carboxymethycellulose (CMC), welan gum, guar gum, schizophyllan, and other newly developed family members. This review provides a synopsis of EOR polysaccharides, which are rapidly emerging as eco-friendly and tough injectants compared to synthetic polymers.