Probiotics, defined as live microorganisms conferring health benefits, are increasingly recognized for their potential to enhance animal productivity, mitigate environmental impact, and improve overall animal health. Ruminants, including sheep, are significant contributors to greenhouse gas emissions, a key factor in climate change. Literature from 2003 to 2024 was retrieved from PubMed (Medline), Web of Science, and CAB Direct using the keywords: sheep, sustainability, probiotics, methane emission, and greenhouse gas emissions. The inclusion of probiotics in sheep diets demonstrates potential as a methane mitigation strategy through the stimulation of beneficial bacteria and the suppression of methanogenic microbial activity. Probiotics can improve rumen fermentation parameters by increasing volatile fatty acid production, decreasing protozoal numbers, and improving gas production. Additionally, probiotics can sustain intestinal health, boost nutrient digestibility, and strengthen the immune system. Although promising, the variable effectiveness of probiotics underscores the importance of refining formulations and delivery methods, taking into account strain, dose, and administration. Further studies are crucial to understand the underlying mechanisms and maximize their impact on sheep productivity. This review delves into the potential of probiotics to improve growth, health, and environmental sustainability in the sheep industry, drawing on insights from in vitro and in vivo studies.