Phthalates are ubiquitous environmental contaminants and established endocrine disruptors with disproportionate exposure among disadvantaged populations. Food insecurity, a marker of socioeconomic deprivation, may be a modifiable contributor to disparate phthalate exposure among adults. Still, associations between food insecurity and phthalate concentrations remain unclear. We analyzed cross-sectional data from 13,024 adults in eight cycles of the National Health and Nutrition Examination Survey (2003-2018). Using multivariable linear regression models, we assessed associations between food security status (four categories) and percent difference in urinary phthalate metabolite concentrations (spot sample), adjusting for sociodemographic factors, survey year, and urinary creatinine. We assessed effect modification by sex and race/ethnicity. Compared with adults with high food security (70.5%), those experiencing very low food security (7.1%) had significantly higher urinary concentrations of monobenzyl phthalate (MBzP: 25.1%; 95% confidence interval [CI]: 13.2%, 38.2%), mono-n-butyl phthalate (MnBP: 9.6%; 95% CI: 1.1%, 18.8%), higher ∑di-2-ethylhexyl phthalate (12.1%; 95% CI: 2.4%, 22.7%), ∑Butyls (11.4%; 95% CI: 3.9%, 19.4%), and ∑Plastic-associated metabolites (16.0%; 95% CI: 6.4%, 26.4%). Sex and race/ethnicity, respectively, modified the food security-metabolite associations. Stronger associations were observed among females (MBzP, ∑di-2-ethylhexyl phthalate, ∑Butyls, and ∑Plastics), as well as non-Hispanic White, non-Hispanic Black, and other race individuals (MnBP and MBzP). Lower food security was associated with elevated concentrations of several phthalate biomarkers among US adults, with stronger associations seen in certain population subgroups. These findings highlight the need to further investigate food insecurity as a modifiable risk factor to decrease phthalate exposure disparities.