This work presents the extraction and characterization of nanocellulose from agricultural waste (Eragrostis Teff) straw. The proximate analysis of the straw was done with three triplicates and the average value was recorded. The moisture, ash, volatile matter, and fixed carbon content were 6.4%, 5.1%, 74.2%, and 15.6%, respectively. The extractives, lignin, hemicellulose, and cellulose content were found to be 8.5%, 17.5%, 29.5%, 36.5%, respectively. The cellulose was extracted from teff straw by hot water treatment, acid-chlorite delignification, and alkaline hydrolysis process respectively. The values of process parameters such as temperature, time, and sodium hydroxide concentration for alkaline hydrolysis were 57.6 \(℃\) , 1hour, and 4(w/v) % respectively to obtain a cellulose yield of 78.7%. The nano cellulose particles were extracted from the cellulose by acid hydrolysis process (48%v/v sulfuric acid) at 35\(℃\) for 30 min and the yield was 42.8%. The characterization of nano cellulose was done by using Fourier-transform infrared spectroscopy, dynamic light scattering, x-ray diffraction, and thermogravimetry analysis/ derivative thermogravimetry analysis to determine the functional group, particle size distribution, crystallinity, and thermal stability respectively. The Fourier-transform infrared spectroscopy result shows that the reduction and total removal of lignin, hemicellulose, and other amorphous parts found in teff straw. The average particle size was found to be 101.6 nm with a polydispersity index of 0.047. The crystallinity index of teff straw and nano cellulose was 47.7 and 77.1% respectively. The thermogravimetry analysis shows the thermal stability of the nanocellulose sample was lower than that of cellulose and teff straw samples.