Sour orange peel, a by-product of the fruit juice industry, was used as a source of pectin. The effects of temperature (75–95 °C), time (30–90 min), and liquid–solid ratio (20–40, v/w) were investigated on yield, methoxylation degree (DE), and galacturonic acid content using a Box–Behnken design and response surface methodology. The highest extraction yield (17.95 ± 0.3%) was obtained at temperature of 95 °C, time of 90 min, and liquid–solid ratio of 25 (v/w). The DE values for the pectin ranged from 17% to 30.5%, indicating that the pectin was low in methoxyle. The emulsifying activity of pectin extracted under optimal conditions was 45%. The emulsions were 86.6% stable at 4 °C and 71.4% at 23 °C after 30 days of storage. The pectin exhibited Newtonian flow at low concentrations (≤1.0%, w/v); as the concentration increased, pseudoplastic flow became dominant.