Oil palm frond (OPF) waste is one of the sustainable raw materials obtained after pruning of the OPFs. The objective of this study is to produce cellulose nanocrystals (CNC) from OPFs by chemo-mechanical treatment. The multi-step process started with removal of extractives, wax and pectins by soxhlet extraction, followed by removal of lignin using sodium chlorite and 10% (v/v) acetic acid. The bleached samples were then soaked in potassium hydroxide to remove the hemicellulose and finally underwent acid hydrolysis with 64% (v/v) sulphuric acid hydrolysis for 1 h. The CNC obtained were characterised using transmission electron microscopy (TEM), X-ray diffractions (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analyser (TGA). The TEM images showed that the fibres were well dispersed and the treatment had reduced the size of fibres with average dimensions of 9.88 nm in diameter and 504.12 nm in length. The XRD results showed that the crystallinity index of the extracted cellulose fibres was 52.3% in comparison with the raw OPF, 35%. The results from FTIR analysis showed some differences in the peaks and some were shifted due to removal of some components in the fibres. The TGA confirmed that the CNC had improved its thermal property by having an onset temperature of 258.34°C in comparison with the raw OPF, 197.48°C. This isolated CNC has great properties and can be used in many applications such as in biomedical field, food industry, cosmetics and wood products.