In bacteria, σ factors are essential for transcription initiation. Knowledge about their regulons (i.e., genes transcribed from promoters dependent on these σ factors) is the key for understanding how bacteria cope with the changing environment and could be instrumental for biotechnologically motivated rewiring of gene expression. Here, we characterize the σ ^I regulon from the industrially important model Gram-positive bacterium Bacillus subtilis . We reveal that σ ^I affects expression of ∼130 genes, of which 16 are directly regulated by σ ^I , including genes encoding proteins involved in iron homeostasis. Detailed analysis of promoter elements then identifies unique sequences important for σ ^I -dependent transcription. This study thus provides a comprehensive view on this underexplored component of the B. subtilis transcription machinery.