Mangrove forests provide a wide range of goods and services that sustain communities around the world. This paper explores utilization patterns of extractable mangrove resources by communities within the proposed Kenya–Tanzania transboundary conservation area (TBCA). Some 152 household surveys and 12 nominal group technique discussions were carried out. At least 16 direct-use products were reported to be extracted from the mangroves, with 90% of households found to use mangrove products. Changing patterns of mangrove use in the areas and accessibility point towards unsustainable utilization and promote illegal activities. Mangrove use patterns also show a high level of mangrove dependence by communities for their livelihood. Overharvesting of mangrove wood products is reported to be the major threat facing the forests. There is a need to address the problems of open access through capacity building and awareness creation, development and implementation of harvest plans, and introduction of alternative livelihood options. The results of this study can be used to inform development of the proposed TBCA as well as the establishment of a conservation policy in order to contribute to sustainable utilization of mangroves. These findings are important within the TBCA as well as similar environments around the world.