Background and aims <p>Iron oxide-bound phosphorus (P) constrains plant P acquisition in agricultural soils. However, the ability of non-mycorrhizal fungal isolates originally obtained as endophytes to influence plant access to Fe-bound P remains poorly understood. We tested whether fungal isolates from Ericaceae roots can alter lettuce access to Fe-bound phosphorus through root traits and rhizosphere processes.</p> Methods <p>Lettuce was grown in a controlled system supplied with Fe-bound P at three levels and inoculated with four phylogenetically distinct fungal isolates from ericaceous roots. Plant growth, biomass allocation, root architecture, soil available P, acid phosphatase activity, and plant P concentrations were quantified. Multivariate analysis integrated soil, root and plant responses.</p> Results <p>Fungal inoculation induced isolate-specific shifts in plant growth, biomass allocation and root architecture. Under Fe–P addition, responsive isolates increased 0–0.5&#xa0;mm root length by 7%–183% relative to control, and this trait was positively associated with apparent P recovery efficiency. Inoculated treatments showed elevated acid phosphatase activity and altered available P, consistent with biological P mobilization and P capture. Root and leaf P concentrations increased in an isolate- and P-dependent manner, and responsive treatments increased total P uptake by 14%–153% relative to the control. Multivariate analyses revealed a soil–root–plant response pattern linking fungal-associated variation in root traits, root–substrate P dynamics and plant P uptake.</p> Conclusions <p>Fungal isolates from Ericaceae roots altered lettuce responses to Fe-bound P through coordinated changes in fine-root architecture, root–substrate P dynamics and P uptake. Selected isolates showed potential for improving acquisition of low-solubility Fe-bound P.</p>