In this study, changes in PFAS bioavailability was assessed following the addition of RemBind® (1-10% w/w) to PFAS-contaminated soil. PFAS concentrations in soil were determined using LC-MS-MS (USEPA method 537 / ASTM D7979-17) while PFAS bioavailability was assessed using an in vivo mouse model following PFAS quantification in target organs (liver and kidney). Ʃ28 PFAS concentrations in contaminated soil ranged from 2.3 to 25.4 mg kg-1 with PFOS being the major constituent (1.2-21.5 mg kg-1). Following determination of the linearity of PFAS accumulation in target organs (i.e. dose-response study undertaken with reference compounds at 0.01, 0.1, 1.0, 2.5 mg kg-1), PFOS relative bioavailability was assessed in untreated and RemBind® treated soil (5% w/w). In untreated soil, PFOS relative bioavailability ranged from 75.7 ± 8.8% to 107.2 ± 3.5% with differences attributed to soil physicochemical properties which may influence electrostatic and hydrophobic interactions. However, when PFOS relative bioavailability was assessed in soil amended with 5% w/w RemBind®100, relative bioavailability was reduced to 18.4 ± 1.7% to 26.1 ± 0.9% with similar results observed when RemBind®300 (5% w/w) was utilised (17.2 ± 2.2% to 22.5 ± 1.0%). Results from this study highlight that the use of soil amendments have the potential to reduce PFOS relative bioavailability (in addition to leachability) thereby reducing exposure to soil-borne contaminants.