<p>Magnetic dispersive solid-phase extraction (MDSPE) coupled with deep eutectic solvent-based dispersive liquid–liquid microextraction (DES–DLLME) and followed by HPLC–FL was applied for extraction and determination of ultra-trace amounts of six phenethylamines (PEAs) in sport and bodybuilding supplements samples. Magnetic nanoparticles of Fe₃O₄@SiO₂@APTA-BBDC were synthesized and employed as sorbent in the DSPE step. After the analytes were extracted from the aqueous solution using nanoparticles during the MDSPE step, they were subsequently recovered in 1.5 mL of acetone. Fifteen microliters of DES were dissolved in the collected acetone, and the resulting solution was promptly injected into 5 mL of an aqueous medium to carry out the DLLME procedure. The integration of these two methods offers not only exceptionally high enrichment factors but also enables efficient extraction of analytes from complex matrices. Under optimal conditions, the method exhibited intra-day and inter-day %RSD values of 1.8–4.7% and 2.7–6.3%, respectively, based on seven replicate measurements of 50&#xa0;µg kg⁻¹ phenethylamines (PEAs) in sport and bodybuilding supplements. Linearity was confirmed over a concentration range 5–250&#xa0;µg kg⁻¹, with detection limits spanning from 1.5 to 3.0&#xa0;µg kg⁻¹. Method accuracy was evaluated by spiking real supplement samples with varying PEAs concentrations, yielding relative recoveries between 91% and 109%.</p> Graphical Abstract <p></p>