Drug-resistant shigellosis is increasing, particularly among men who have sex with men (MSM). During July-October 2022, an extended-spectrum β-lactamase-producing Shigella sonnei cluster of 9 patients was identified in Chicago, of whom 8 were MSM and 6 were festival attendees. The cluster also included 4 domestic travelers to Chicago. Sexual health care for MSM should include shigellosis diagnosis and prevention.