Heat-induced aggregation and gelation in lentil protein isolate (LPI) were studied over pH levels (pH 2–9), protein concentration (1–13%, w/w), and heating time (0.5–16 h). The LPI gels were formed from both fibrillar and particulate aggregates at pH 2 and 7, respectively. The gels formed from fibrillar aggregates at pH 2 were translucent and showed homogeneous and highly interconnected networks. While lentil protein showed weak gelling capacity, the gels prepared from LPI aggregates possessed good mechanical properties, and the optimized gel demonstrated a compressive strength of 2.37 kPa and a water holding capacity of 80.62%. The gelling mechanism study suggests that the high aspect ratio allowed fibrillar aggregates to build a higher level of structures with positive characteristics along with other attractive interactions including hydrophobic interactions and disulfide bonds to build strong gels. Therefore, this research has developed a new strategy to prepare improved lentil protein gels for food texturization from LPI fibrillar aggregates.