The effects of four treatments of Pleurotus eryngii (king oyster mushroom) as replacements for pork back fat were evaluated for the physicochemical, technological, and sensory properties; nitrite content; and amino acid profile in pork sausages. Five batches were manufactured: one control (formulated with pork back fat) and four treatments with raw, boiled, deep-fried, and fried P. eryngii to replace the pork back fat in sausages. The results indicated that the fat content and energy value decreased, while the protein, moisture, total dietary fiber content, cooking loss, and water-holding capacity of the modified sausages increased. All samples were judged acceptable for their sensory characteristics, with the best one being the sausage containing deep-fried P. eryngii. The raw and fried P. eryngii decreased the residual nitrite content in the sausages. Boiled P. eryngii enhanced the essential amino acids content in the sausages, while the other P. eryngii treatments improved the nonessential amino acid content. In summary, P. eryngii may potentially replace fat in sausages. PRACTICAL APPLICATION: In manufacturing pork sausages, the mushroom P. eryngii can substitute pork back fat to improve the nutritional quality by reducing fat and energy value, while enhancing the protein and total dietary fiber content in the sausages. Raw and fried P. eryngii decreased the residual nitrite content in the sausages. This study provides a basis for preparing healthier alternatives to traditional sausages by substituting pork fat with mushrooms.