In this work, cellulose was successfully extracted from pineapple leaf waste by 0.75 M NaOH at 90oC and 5 M HNO3 at 70oC for 1.5 h and 5 h, respectively. The obtained cellulose fibres, with average diameters of 150-300 nm, were converted to carboxymethyl cellulose (CMC) by esterification. The pure cellulose was soaked in a solution mixture of isopropanol and NaOH for 2 h. It was then reacted with chloroacetic acid (MCA) at 60oC for 1.5 h. The optimum conditions for carboxymethylation were found to be 5 g cellulose, 1.5 g MCA, and 15 ml 16% w/v NaOH. The obtained CMC had a high degree of substitution (DS) of 2.3. The properties of CMC were determined.