Amid growing consumer demand for low-sugar foods, conventional high-methoxyl pectin (HMP) faces limitations due to its requirement for high soluble solids (>55%) to form gels. This study introduces pectin from Nicandra physalodes (Linn.) Gaertn. (NPGP) as a novel resource capable of forming self-supporting gels under low-sugar or even sugar-free acidic conditions. Comprehensive structural characterization revealed that NPGP possesses a high molecular weight (Mw 516.01 kDa), a linear backbone rich in homogalacturonan (HGA, 79.47%), a low degree of methoxylation (DM 38.42%), and an elevated degree of acetylation (DAc 5.78%). In contrast, commercial HMPs required sucrose concentrations ≥60% for gelation, whereas NPGP achieved optimal textural properties at only 40% sucrose under acidic conditions (pH 3.0). Compared to HMP gels, NPGP sugar-acid gels demonstrated superior springiness, self-healing capability, and water-holding capacity, although with lower gel strength. Mechanistic investigations, including urea/SDS disruption, isothermal titration calorimetry, and scattering techniques, revealed that NPGP forms aggregates through the parallel alignment of its extended linear chains, which subsequently develop into an interconnected network. Hydrogen bonding, provided by abundant carboxyl and hydroxyl groups, was identified as the primary gelation driving force, while methyl ester and acetyl groups contributed hydrophobic interactions as secondary stabilizing factors. These findings establish NPGP as a promising pectin resource for low-sugar applications and provide new insights into structure-driven gelation mechanisms that extend beyond the conventional DM classification system.