Summary Uncultured members of the Chloroflexi phylum are highly enriched in numerous subseafloor environments. Their metabolic potential was evaluated by reconstructing 31 Chloroflexi genomes from six different subseafloor habitats. The near ubiquitous presence of enzymes of the Wood–Ljungdahl pathway, electron bifurcation, and ferredoxin‐dependent transport‐coupled phosphorylation indicated anaerobic acetogenesis was central...