Abstract Development of herbicides with novel modes of action is crucial for weed control and to hinder herbicide resistance. An attractive novel herbicidal target is plant DNA gyrase, which has been demonstrated to be effectively inhibited by the known antimicrobial ciprofloxacin. Despite this good herbicidal activity, ciprofloxacin is not suitable as a herbicide due to its antimicrobial activity; therefore, a diverse library of analogues was analyzed to gain insight into the aspects required for herbicidal activity. This analysis revealed that significant structural modifications were tolerated and that the fluoride at C‐6 and a cyclic amino group at C‐7 were not crucial for herbicidal activity. The analysis also revealed that these modifications also affected the antibacterial activity with one compound demonstrating good herbicidal activity and weak antibacterial activity, against both Gram‐positive and Gram‐negative bacteria.