Abstract Comprehensive mitigation of gas emissions from swine manure was investigated. Additives addition for mitigation of gas from the manure has been developed. Sargassum horneri, seaweed masking strategy controlled gas by 90%-100%. Immediate reduction in emitted gas and improving air quality has been determined. Microbial consortium with seaweed completely controlled gas emissions by 100%. Gas emissions from swine farms have an impact on air quality in the Republic of Korea. Swine manure stored in deep pits for a long time is a major source of harmful gas emissions. Therefore, we evaluated the mitigation of emissions of ammonia (NH3), hydrogen sulfide (H2S) and amine gases from swine manure with biological products such as seaweed (Sargassum horneri) and a microbial consortium (Bacillus subtilis (1.2 × 109 CFU/mL), Thiobacillus sp. (1.0 × 1010 CFU/mL) and Saccharomyces cerevisiae (2.0 × 109 CFU/mL)) used as additives due to their promising benefits for nutrient cycling. Overall, seaweed powder masking over two days provided notable control of over 98%-100% of the gas emissions. Furthermore, significant control of gas emissions was especially pronounced when seaweed powder masking along with a microbial consortium was applied, resulting in a gas reduction rate of 100% for NH3, amines and H2S over 10 days of treatment. The results also suggested that seaweed powder masking and a microbial consortium used in combination to reduce the gas emissions from swine manure reduced odour compared with that observed when the two additives were used alone. Without the consortium, seaweed decreased total volatile fatty acid (VFA) production. The proposed novel method of masking with a microbial consortium is promising for mitigating hazardous gases, simple, and environmentally beneficial. More research is warranted to determine the mechanisms underlying the seaweed and substrate interactions.