The 2022 monkeypox (MPX) outbreak was a source of consternation and stress among men who have sex with men (MSM)—the population disproportionately affected by the recent MPX outbreak. Individuals at high‐risk for MPX (e.g., MSM, sex workers) were prioritized for vaccination during early state and city health department vaccine initiatives across the U.S., but little is known about how the MSM sex work market was affected by the MPX outbreak in U.S. cities where MPX incidence was particularly high. To better characterize the potential relationship between MPX incidence and MSM sex worker advertising at the height of the U.S. MPX outbreak, we monitored advertising volume on an Internet advertising platform popular among MSM sex workers and compared these data to city and county health department MPX case reporting data during a 13‐week period (July 2nd, 2022‐ September 24th, 2022) in three U.S. cities with peak MPX incidence: Chicago, New York City, and San Francisco. In each of these cities, we observed a decline in advertising during or immediately following study week(s) with the highest number of weekly MPX cases during the study period, recognizing that observed decreases in advertising could be attributed to transient increase(s) in advertising during large‐scale LGBT festivals occurring during the study period.