The presence of black carbon (BC) and its interaction with polycyclic aromatic hydrocarbons (PAHs) in mangrove sediments were studied for the first time. The study included an oil contaminated mangrove and two other sites of different character. BC content ranged from 0.03% to 0.47% (dry weight sediment), reaching a maximum of 9% of the total organic carbon. Cluster analysis indicated strong BC and high molecular weight (HMW) PAH association but no relationship was found between BC and alkylated PAHs. The ratio C4Ph/BaP was used to verify differences in the mobility of alkylated and HMW PAHs along a core from the oil contaminated site. Results for the solid–water coefficient of distribution (Kd in l kg−1) for pyrene were similar using untreated sediment samples (log Kd 4.66 ± 0.03) and chemo-thermal oxidation (CTO) residues (log Kd 4.39 ± 0.03), confirming the importance of BC in the partitioning of PAHs. However, the resulting BC-normalized distribution coefficients (log KBC 7.1–7.4 μg ) were greater than published values, probably because of the presence of other hydrophobic phases in the refractory organic matter pool. In addition, BC normalization of pyrene concentration in mangrove crabs reduced the variability in calculated bioaccumulation factors vs. organic carbon-normalized concentrations for the sites. The evidence agrees with the general view of BC particles controlling the fate of PAHs in sediments, but also points out the necessity for studying the process in further detail when considering organic matter-rich mangrove sediments.