This study investigates Ag-doped Fe₃O₄ nanofluids for enhanced convective heat transfer. Nanoparticles were synthesized using ultrasound-assisted and minireactor-based methods, characterized through analytical techniques, and dispersed in water to evaluate their stability and thermal conductivity. A lab-scale setup was used to analyze convective heat transfer, pressure drop, and friction factor in a pinched tube, an advanced heat transfer system. Results demonstrate a significant Nusselt number increase from 22.886 to 62.365 at a Reynolds number of 6160 ± 75 when 0.02 vol.% of minireactor-synthesized Ag-doped Fe₃O₄ nanoparticles were added to water. These findings highlight the potential of these nanofluids for improving thermal performance in practical applications.