Introduction: Numerous locally accessible plants in Nepal are left unseen. So, exploring their antioxidant activity for medicinal purposes can be beneficial in treating various diseases. Antioxidants have great importance in terms of reducing oxidative stress that causes damage to biological molecules. The qualitative analysis of chemical constituents using a chromatographic technique like TLC plays a pivotal role in this aspect. The present study aimed at performing chemical profiling using thin-layer chromatographic technique and evaluation of the antioxidant activity of selected medicinal plants. Methods: Firstly, TLC profiling of 70% methanolic extracts of eighteen medicinal plants was done using preparative TLC plate in two different ratio of chloroform, methanol and water. Then, antioxidant activity was tested by DPPH (2, 2-diphenyl-1-picrylhydrazyl) free radical scavenging assay by using a 96 well plate method at wavelength 510 nm in which Trolox was taken as standard. Results: Flavonoids, tannins, saccharides, and phenols were identified from TLC profiling. The yield value of Sapium insigne leaves extracts i.e. 20.52% was highest and Monochoria vaginalis leaves possess the least i.e. 3.93%. Solena heterophylla leaves extract with IC50 amount i.e. 21 µg/ml was found most potent among all the plant extracts. Conclusion: The results imply that the extract of ethnomedicinal plants is rich with a variety of phytochemicals, which can be used as natural antioxidants. However, further studies are warranted to isolate and identify the chemical and biological properties of obtained extracts for the provision of scientific evidence for traditional uses.