Saint Martin Island (SMI), the only coral island in Bangladesh, is located in the Bay of Bengal and has been identified as a marine protected area (MPA). Littering cigarette butts (CBs) waste in an ecologically sensitive environment can have numerous adverse effects. The purpose of this research is to investigate the abundance and density of CBs in SMI and to assess the pollution status using the Cigarette Butt Pollution Index (CBPI). This study is conducted based on the visual survey method in the three types of land use zones of SMI. During the peak season, the investigation was carried out from 9 a.m. to 5 p.m. in December 2023. A total of 4481 CBs item were counted, and the density ranged from 0.37 to 1.76 m− 2 with an average value of 0.99 m− 2 across 12 sampling campaigns. The highest density was observed at service zones, and the fishing zones had the lowest density. The calculated CBPI values revealed that 75 % of the sampling stations were in the “severe pollution” while 25 % were classified as “high pollution” status, underscoring the prevalence of hazardous CBs across most areas of SMI. To tackle these issues requires regulatory measures, public awareness initiatives, and community involvement. Effective waste management and eco-friendly product promotion can help reduce CBs pollution risks in marine protected islands.