Phenolic compounds are dietary bioactive compounds that are available in foods and beverages. They are produced by the plant and/or by the mushrooms, naturally. Some of the natural phenolic compounds were also used in dietary supplements in the pharmaceutical or food industries. For simultaneous analyses of phenolic compounds in one injection, a rapid and sensitive method was developed for twenty-seven natural compounds using reverse-phase high-performance liquid chromatography (RP-HPLC) coupled with diode array detector (DAD). The linear gradient elution systems of 0.1% acetic acid-methanol were used, and the analyzing time was 61 minutes. The method was validated with linearity, relative error, reproducibility, LOD values. Relative standard deviation between (n = 7) within and between days for reproducibility is less than 10%, and relative error (or recovery) is less than 5%. The method exhibited excellent linearity (R2>0.999), good precision (RSD<6.1%), recovery (97.6–104.1%) and limits of detection (0.23–28.81 µg/m1) and quantification (1.62– 87.29 µg/m1). The detection of compounds was performed at 220 nm, 280 nm, and 330 nm. The developed method for the rapid determination of phenolic compounds using RP-HPLC can be used to identify the availability of these phenolic compounds in natural and commercial products.