The study investigates the relationship between microbial diversity and multifunctionality in terrestrial ecosystems, using two large-scale databases from global drylands and Scotland. The results show that soil microbial diversity positively correlates with multifunctionality, which includes processes such as nutrient cycling, primary production, litter decomposition, and climate regulation. This positive relationship was maintained even when controlling for multiple multifunctionality drivers, including climate, soil abiotic factors, and spatial predictors. The findings suggest that any loss in microbial diversity will likely reduce the multifunctionality of terrestrial ecosystems, impacting services such as climate regulation, soil fertility, and food and fiber production. The study provides empirical evidence that microbial diversity is crucial for maintaining the multifunctionality of ecosystems and highlights the need to protect soil microbial diversity from global environmental changes.The study investigates the relationship between microbial diversity and multifunctionality in terrestrial ecosystems, using two large-scale databases from global drylands and Scotland. The results show that soil microbial diversity positively correlates with multifunctionality, which includes processes such as nutrient cycling, primary production, litter decomposition, and climate regulation. This positive relationship was maintained even when controlling for multiple multifunctionality drivers, including climate, soil abiotic factors, and spatial predictors. The findings suggest that any loss in microbial diversity will likely reduce the multifunctionality of terrestrial ecosystems, impacting services such as climate regulation, soil fertility, and food and fiber production. The study provides empirical evidence that microbial diversity is crucial for maintaining the multifunctionality of ecosystems and highlights the need to protect soil microbial diversity from global environmental changes.