Bees provide essential pollination services to managed and wild ecosystems but are threatened globally by multiple stressors, including exposure to contaminants. Perfluorooctane sulfonate (PFOS), a persistent contaminant that accumulates and biomagnifies up the food chain, occurs in a wide range of contaminated environments. Guidelines for ecological receptor exposure to PFOS exposure are lacking, including for bees. In this exposure effect study, small whole colonies of Apis mellifera (2500 bees) were exposed to PFOS ranging from 5 to 20 µg L-1 in sugar syrup over a five-week period using a purpose-built cage system. The PFOS concentrations spanned environmental water concentrations reported and concentrations that bees are known to access. A range of behavioural and biomolecular responses were monitored including lipid peroxidation and proteomics. Bee tissue, honey and faecal matter were analysed using isotope dilution combined with Liquid Chromatography Tandem Mass Spectrometry adapted for bee tissue and honey matrices. Brood development and newly emerged bee weight decreased significantly at ≥ 5 µg L-1 and gastric health was adversely affected with any PFOS exposure compared to the controls. Consumption of sugar syrup decreased with increasing PFOS concentration and was significantly lower than the control at even at the lowest exposure concentration of ≥ 5 µg L-1. PFOS was detected in adult and newly emerged bee tissue with a mean bioaccumulation factor (BAF) of 1.72 and 0.69, respectively, and transferred to both honey and faeces. The findings provide clear evidence that environmental PFOS exposures can adversely affect honey bee colonies, causing biomolecular and behavioural changes in bees and transfers to honey. Our study contributes to the developing evidence to support ecological protection guidelines and has implications for food security, food chain exposure and ecological health.