Homogenization has been traditionally used in the dairy industry to reduce the particle size of milk fat globules and prevent cream separation. Pressures of 3–20 MPa have historically been applied to a wide of variety of dairy products to improve texture, stability, flavor, and shelf-life. High-pressure jet (HPJ) technology is a novel process that can achieve processing pressures of up to 600 MPa. The HPJ contains a diamond nozzle (75 to 400 μm diameter) that forces liquid into a jet stream, differing from high-pressure homogenization that uses a valve (HPH). Previous studies on pasteurized skim milk displayed an increase in viscosity, foaming, and emulsifying properties. The objective of this study was to evaluate the changes in casein-fat interaction of pasteurized and conventionally homogenized whole milk processed through HPJ-processing at 0 to 500 MPa (125 MPa increments), centrifuged, and freeze-dried. After centrifugation at 100,000 × g for 30 min, 3 distinct layers: cream (top), whey (middle), casein (bottom) was observed. The dry weight of the cream fraction decreased (0.67 ± 0.03 g to 0.11 ± 0.04 g) and the casein fraction increased (0.44 ± 0.01 g to 1.21 ± 0.05 g), while the whey fraction slightly decreased (1.46 ± 0.04 g to 1.21 ± 0.03 g) with increasing pressure and compared with the control (0 – 500 MPa). Fat content was also measured on the dry fractions to confirm migration of fat to the casein fraction. Fat content of the cream fraction decreased from 0.59 ± 0.06 g to 0.08 ± 0.04 g, while the fat content of the casein fraction increased from 0.02 ± 0.02 g to 0.44 ± 0.05 g. Casein-fat stability and aggregation was highly affected by HPJ processing. It is suggested that with increasing pressure, casein micelle and fat globule dissociation occurs and individual caseins interact with triglycerides to form stable casein-triglyceride aggregates. The results from this study will provide further applications for high-pressure jet processing in dairy foods.