A simple green analytical method for the quantification of sweet orange and lavender essential oils (EOs) content in blends was developed using synchronous fluorescence first derivative spectra and sample preparation by surfactant-free microemulsions (SFMEs). Excitation and emission wavelengths pairs (Absorbance measurements in the excitation wavelength/Absorbance measurements in the emission wavelength) were determined for both EOs (at 336/436 nm for sweet orange and at 330/388 nm for lavender). Optimization was conducted to establish the condition to prepare the SFMEs systems: 50 microlitres of oily phase containing EO diluted in octan-1-ol (1:4, v/v), 2.0 mL of water and propan-1-ol up to 5.0 mL final volume. Different proportions of EO in the oily phase were prepared for analytical curves construction to monitor curve s sensibility. Synchronous fluorescence measurements were performed, and the acquired data were corrected by inner filter effect. Considering the first derivative of the synchronous scanning, data were extracted at 316.8 nm (Stokes shift = 100 nm) and 352.0 nm (Stokes shift = 58 nm) for sweet orange and lavender EOs, respectively, with determination coefficients above 0.99. Limits of quantification of 8.0 micrograms mL-1 and 65.8 micrograms mL-1 were obtained indicating that 0.46 percent of sweet orange and 3.69 percent of lavender EOs can be quantified in mixtures. Simulated blends (25:75 percent, 50:50 percent and 75:25 percent, volume proportions) were also evaluated with recoveries of 71.5 – 128.9 percent and coefficient of variation between 3.1 percent – 11.6 percent. Additionally, the method s greenness was evaluated through three green metrics (Analytical Eco-Scale, GAPI, and AGREE) with aligned results.