Atenolol is a medication belonging to the class of drugs known as beta blockers, used to treat high blood pressure (hypertension) and irregular heartbeats (arrhythmia). Its presence in the environment has serious impact for human, animals and water ecosystem. In this context, the aim of this study was to develop a simple voltammetric method for the determination of atenolol (ATN) using a carbon-paste electrode modified with nanomaterials TiO₂ and GO/TiO_2. The analytical performance of the modified sensor was evaluated using square wave voltammetry and cyclic voltammetry in 0.1 mol L ⁻¹ acid sulfuric solution (H₂SO₄), pH 2. The nanocomposite electrode CPE/GO/TiO₂ exhibits excellent electrocatalytic activity towards ATN oxidations at 0.1 mol L ⁻¹ H₂SO₄ compared with unmodified carbon-paste electrodes CPE and electrodes modified with titanium oxide CPE/TiO₂. Different experimental and conditional parameters were optimized such as supporting electrolyte, pH, amplitude, frequency, etc. Under optimal conditions, linear calibration curves were obtained ranging from 1.7 to 23.2 µmol L ⁻¹ for ATN with detection limits of 0.05 μmol L ⁻¹, respectively. The modified nanocomposite CPE/ GO/ TiO₂ sensor showed good sensitivity and good repeatability (RSD ≤ 0.61%) for ATN determination. The proposed sensor is mechanically robust and presented reproducible results and a long-term useful life. In order to verify the usefulness of the developed method, the nanocomposite sensor CPE/GO/TiO_2, was applied to the detection of atenolol in a real sample (pharmaceutical tablets without any pre-treatment). Excipients present in the tablets did not interfere with the assay. Recoveries ranging from 97.7% to 106 % were obtained. The results proved that the CPE/ GO/ TiO₂ voltammetric sensor might be successfully applied in the routine quality control of ATN in complex matrices.