Blue fenugreek, also known as blue melilot, is an herbaceous annual aromatic plant and is also used as a forage crop for its green fodder. Notwithstanding the numerous researches conducted on various aromatic and medicinal plant species, there is a notable paucity of investigation into the impact of fertilization, phosphorus (P) in particular, on the dry herb yield, essential oil content, essential oil yield and volatile compound composition of blue fenugreek. This two-year field study, conducted in Tekirdağ, eastern Thrace (southeastern Europe), employed a randomized complete block design with three replications to evaluate the effects of different P levels [0 (control), 30, 45, 60, 75, and 90 kg P ha^-1] on the essential oil yield and volatile compound composition of blue fenugreek. The highest essential oil yield (1.58 kg ha^-1) was recorded at the 90 kg P ha^-1 application rate. A total of twenty-five volatile oil compounds were identified, comprising 97.21-98.95% of the essential oil and showed four dominating constituents in blue fenugreek, namely phytol (19.97-22.04%), n-pentacosane (15.99-18.88%), tiglic aldehyde (13.49-16.07%) and tetradecanoic acid (11.98-14.20%). The highest concentrations of n-hexanal (1.20-1.22%), methyl benzoate (0.97-0.98%), L-menthone (0.83%), and heptadecane (0.73-0.80%) were obtained from the control and the 30 kg P ha-1 dose. The highest concentration of 1-octadecanol (5.04%), farnesylacetone (3.13%), (E)-β-damascenone (1.48%), dimethyl tetradecanedioate (2.43%), and (E)-β-ionone (1.90%) were found in the control. On the other hand, increasing P levels resulted in an increase in the content of 2-methyl-2-butene (0.89-0.92%), 1-octen-3-ol (0.48-0.50%), (E)-geranylacetone (0.87-0.91%), phytol (22.03-22.04%), tetradecanoic acid (14.19-14.20%) and n-pentacosane (18.81-18.88%). Additionally, principal component analysis (PCA) revealed significant differentiation among P levels.