Mercury exposure risk can be regulated by complex biogeochemical drivers at multiple scales that determine mercury loading, bioavailability, and trophic transfer. Tissue data from biosentinel taxa can be useful to estimate mercury risk and protect wildlife and human health. Freshwater predatory invertebrates like dragonfly larvae are increasingly being used as biosentinels to monitor mercury regimes. Because the intrinsic and extrinsic drivers that regulate their mercury assimilation are not fully understood, we analyzed trends in the literature, laboratory, and field. We conducted a meta-analysis and estimated that freshwater predatory invertebrates biomagnify mercury by factors of 2.1±0.2 to 4.3±0.3, with 95% credible intervals ranging from 1.6 to 5.3. Methylmercury trophic magnification factors for communities including vertebrates and primary producers were 18.6±6.2 to 54.1±7.7% higher than invertebrate sub-communities alone. Biomagnification was influenced by exposure concentration and invertebrate taxonomic and functional diversity. We also conducted a series of laboratory experiments to measure mercury trophic transfer from dosed prey to dragonfly larvae over time across exposure levels. Preliminary data suggested that dragonfly mercury concentrations responded to dietary exposure in as little as 7 days and reached equilibrium in as little as 40 days. Dragonflies biomagnified methylmercury by preliminary factors of 1.0±0.1 to 3.4±0.2, influenced by exposure concentration and intrinsic drivers like development and taxonomy. We also explored the influence extrinsic drivers like surrounding land cover on mercury levels by sampling dragonfly larvae from 104 diverse sites throughout the complex Willamette River Basin in Oregon, USA. Preliminary dragonfly mercury concentrations varied by 88 ± 14.7% within tributary catchments, negatively correlated with finer-scale surrounding urban cover and positively correlated with broader-scale surrounding forest cover. Agriculture had habitat-dependent influences, associated with higher dragonfly mercury in wetland sites and lower dragonfly mercury in lentic sites. This research helps expand scientific understanding of the intrinsic and extrinsic determinants of mercury cycling in dragonfly larvae and other freshwater predatory invertebrates.