Pyrethroids are the active ingredients in numerous indoor and outdoor insecticides. They are extensively used in agriculture, residences, and public spaces, resulting in human exposures associated with adverse health outcomes. Human biomonitoring studies typically assess human exposures to pyrethroids using a common metabolite of different pyrethroids, 3-PBA (3-phenoxybenzoic acid), as a biomarker of exposure. The aim of this systematic review is to provide a comprehensive summary of pyrethroids exposures in different populations worldwide. A search of PubMed, Embase, and Scifinder identified 421 publications potentially reporting urinary 3-PBA levels. From these publications, a total of 59 studies were identified as relevant after the removal of duplicates and studies that did not meet predetermined inclusion criteria. These papers reported 3-PBA levels in 21, 11, 20, and 12 cohorts of children, pregnant women, environmental exposed adults and occupationally exposed adults, respectively. Geometric mean (ng/mL) 3-PBA levels ranged from 0.32 to 2.06 in children, 0.12 to 1.77 in pregnant women and 0.17 to 12.7 in environmentally exposed adults. These levels were lower compared to occupationally exposed adults, typically agricultural workers were their geometric mean creatinine adjusted [mg/g cre] 3-PBA levels ranged from 0.32 to 23.8. Meanwhile, NHANES reports from years 1999 to 2014, display geometric mean (ng/mL) ranges from 0.325 to 0.549 for children and 0.267 to 0.427 for environmentally exposed adults living in the USA. In contrast with the previous reported papers, the NHANES reports show significantly lower levels of 3-PBA in children and adults. Altogether, human populations worldwide, including susceptible populations, are exposed to pyrethroid insecticides, an observation that raises human health concerns.