Emerging evidence highlights the potential of bioactive peptides, derived from dietary sources, to modulate lipid metabolism and the inflammatory response in Metabolic dysfunction-Associated Steatotic Liver Disease (MASLD). The disease is characterized by an abnormal accumulation of liver fat, inflammation and oxidative stress. Furthemore, the production and bioactivity of peptides can be enhanced by novel processing technologies. The aim of this study was to optimize the generation of bioactive peptides from common bean (Phaseolus vulgaris) and pumpkin seed (Cucurbita pepo) proteins using ultrasound-assisted enzymatic hydrolysis and evaluating the impact of pre- and post-treatment of ultrasound on peptide yield, antioxidant capacity, anti-inflammatory and anti-steatotic effect. Ultrasound pre-treatment of pepsin-pancreatin hydrolysates increased significantly the hydrolysis degree, peptide yield and antioxidant capacity, as evidenced by ABTS and ORAC assays, of common bean and pumpkin seed protein hydrolysates compared to controls. However, post-treatment only increased the antioxidant capacity of the hydrolysates. Ultrasound pre-treated hydrolysates were divided into two fractions (<3 kDa and 3-10 kDa) and their biological activities were evaluated in cell models. Fractions of common bean and pumpkin seed hydrolysates suppressed LPS/Palmitic acid-induced inflammation in RAW 264.7 macrophages, reducing nitric oxide production and intracellular reactive oxygen species in a dose-dependent manner. Furthermore, in an Oleic acid/Palmitic acid HepG2 model of hepatic steatosis, the peptides reduced lipid accumulation down to 66.8% compared to untreated cells (measured with ORO staining). RT-qPCR analysis showed that mRNA expression levels of lipid metabolism related genes, specifically fatty acid synthase (FAS) which is involved in lipogenesis and carnitine palmitoyltransferase-1a (CPT1a) related to fatty acid oxidation, were differentially regulated after treatment with common bean and pumpkin seed peptides in the steatosis model. These results demonstrate that ultrasound-assisted enzymatic hydrolysis significantly enhances peptide release and bioactivity, underscoring their strong potential as functional ingredients to combat oxidative stress, inflammation, and lipid disorders.