The aim of this study was to investigate the impact of ultrasonication on the formation of crystalline network of monoglycerides (MGs) and Tween 20 (Tw20) in a continuous matrix of olive oil. Several analytical methods such as differential scanning calorimetry (DSC), confocal and polarized optical microscopy, rheometry, and infrared spectroscopy (FT-IR) were employed to characterize the ultrasonicated oleogel structures. DSC and FT-IR provided evidence that ultrasonication accelerated the crystallization of the β-polymorph of the monoglycerides. Confocal and optical microscopy revealed that ultrasonication resulted in shorter and thinner β-MGs crystals. The addition of Tw20 to the system led to formation of oil-in-oil emulsion gels with the β-MGs crystals acting as Pickering particles. Rheology showed that ultrasonication induced the formation of stronger but with lower yield stress oleogels. Overall, ultrasonication can modulate the structure of MGs-based crystallized networks, thereby influencing the thermomechanical properties, which could be beneficial for fat substitution in food products.