The majority of liver-related illnesses are caused by occupational and domestic exposure to toxic chemicals like formaldehyde (FA), which is widely common in Africa and the world at large. Hence, measures should be taken to protect humans from its hazardous effects. This study, therefore, examines the protective potential of Ganoderma lucidum (100 mg/kg body weight) on formaldehyde-induced (40%) liver oxido-inflammation in male rats. Male Wistar rats, 150–200 g, were allotted into four groups of 10 animals as follows: Group 1 was orally treated with 1 mg/mL distilled water, Group 2 was exposed to a 40% formaldehyde vapor environment for 30 min per day, Group 3 was orally treated with 100 mg/kg ethanol extract of Ganoderma lucidum, and Group 4 was co-administered formaldehyde and 100 mg/kg ethanol extract of Ganoderma lucidum. Rats were then sacrificed 24 h after administering the last dose of treatment, and the livers were excised. Ganoderma lucidum significantly reversed the formaldehyde-mediated reduction in body and organ weight. Ganoderma lucidum administration significantly prevented oxido-inflammation by reducing the levels of hydrogen peroxide and malondialdehyde and increasing the activity of antioxidant enzymes and glutathione contents, as well as the normal level of nitrite and myeloperoxidase production in FA-treated rats. Additionally, Ganoderma lucidum reversed a large decline in proinflammatory markers in formaldehyde. Furthermore, Ganoderma lucidum restores formaldehyde-induced histological alterations in the liver. Collectively, our results provide valuable information on the protective potential of Ganoderma lucidum in protecting formaldehyde-induced liver oxido-inflammation in male rats.