The purpose of the study was to determine the antioxidant activity (AA) and fatty acid (FA) profile of sous-vide beef previously marinated in brine with a 10, 20 and 30% addition of kiwiberry (Actinidia arguta cv. ‘Ananasnaya’) fruit pulp, as well as changes in the parameters studied after 0, 1, 2 and 3 weeks of refrigerated storage in a vacuum package. The FA profile, FRAP (ferric-reducing antioxidant power assay), ABTS (2,2′-azinobis (3-ethylbenzthiazoline-6-acid)), total polyphenols, chlorophylls and carotenoids were also determined in the fruit pulp. Lipid indices for meat were calculated based on the obtained FA profile. The values of FRAP and ABTS of experimental meat products were significantly (p ≤ 0.05) higher than those of control samples but decreased with storage time. The proportion of unsaturated FA in the lipids of sous-vide meat was higher in samples with pulp than in control samples and insignificantly decreased with storage time. Meat marinated with kiwiberry pulp was characterized by a significantly (p ≤ 0.05) higher proportion of ALA (α-linolenic acid) and LA (linoleic acid), considerably affecting the more favorable value of polyunsaturated FA/saturated FA ratio. A troubling finding was the heightened level of palmitic acid (C16:0) in the lipids of beef subjected to 30% kiwiberry pulp, a factor recognized to play a significant role in the development of various diseases. Beef marinated with 20% kiwiberry pulp addition provides greater nutritional and health benefits than other sample variants because of optimal AA and FA profile changes during refrigerated storage.