Mangrove wetlands are some of the most important locations of organic carbon (OC) sequestration and storage in the world on a per area basis. The high stocks of soil OC are driven by generally high burial rates and efficient preservation of organic material over past millennia of relatively slow and consistent sea level rise. Although the global average rate of OC burial in mangrove wetlands is relatively high, the range in the literature varies by up to two orders of magnitude. The objective of this research was to measure burial rates of OC, CaCO3, and nutrients [total nitrogen (TN) and phosphorous (TP)] across a pronounced ecosystem gradient of productivity and salinity in the coastal Everglades of southwestern Florida, USA. Concentrations and burial rates of both CaCO3 (range 13–1233 g m−2 y−1) and TP (range 0.10–1.59 g m−2 y−1) decreased significantly with distance from the Gulf of Mexico. In contrast, there was less spatial variability in OC (134 ± 12 (1 SE) g m−2 y−1) and TN (6.2 ± 0.4 g m−2 y−1) burial rates. However, significant (P < 0.001) regional differences in OC burial rates were observed relative to mangrove primary productivity. Over a centennial timescale, downstream sites buried 14% of annual net primary production, midstream sites buried 22%, and upstream sites preserved less than 10%.