Dihydroquercetin (3,5,7,3',4'-pentahydroxy-flavanone) is known for its powerful antioxidant, organ-protective, and antiinflammatory activities that can be applied to heavy-metal intoxication. The present research objective was to evaluate the possible protective potential of dietary dihydroquercetin in a rat model of subacute (92 days) intoxication with nickel nanoparticles. The experiment involved five groups of twelve male Wistar rats in each. Group 1 served as control. Other groups received nickel nanoparticles as part of their diet. Groups 2 and 4 received nickel nanoparticles with an average diameter of 53.7 nm (NiNP1), while groups 3 and 5 were fed with nanoparticles with an average diameter of 70.9 nm (NiNP2). The dose was calculated as 10 mg/kg b.w. Groups 4 and 5 also received 23 mg/kg b.w. of water-soluble stabilized dihydroquercetin with drinking water. After the dihydroquercetin treatment, the group that consumed 53.7 nm nickel nanoparticles demonstrated lower blood serum glucose, triglycerides, low-density lipoprotein cholesterol, and creatinine. Dihydroquercetin prevented the increase in total protein and albumin fraction associated with nickel nanoparticles intake. The experimental rats also demonstrated lower levels of pro-inflammatory cytokines IL-1β, IL-4, IL-6, and IL-17A, as well as a lower relative spleen weight after the treatment. In the group exposed to 53.7 nm nickel nanoparticles, the dihydroquercetin treatment increased the ratio of cytokines IL-10/IL-17A and decreased the level of circulating FABP2 protein, which is a biomarker of increased intestinal barrier permeability. In the group that received 70.9 nm nickel nanoparticles, the dihydroquercetin treatment inhibited the expression of the fibrogenic Timp3 gene in the liver. In the group that received 53.7 nm nickel nanoparticles, dihydroquercetin partially improved the violated morphology indexes in liver and kidney tissue. However, dihydroquercetin restored neither the content of reduced glutathione in the liver nor the indicators of selenium safety, which were suppressed under the effect of nickel nanoparticles. Moreover, the treatment failed to restore the low locomotor activity in the elevated plus maze test. Dihydroquercetin treatment showed some signs of detoxication and anti-inflammation in rats subjected to nickel nanoparticles. However, additional preclinical studies are necessary to substantiate its prophylactic potential in cases of exposure to nanoparticles of nickel and other heavy metals.