Electrochemical sensors can be developed from the reuse of solid waste through various strategies. Incorporating waste materials effectively reduces the need for new resources, minimizes waste, and promotes sustainable and environmentally friendly sensor production. This approach follows the principles of circular economy and green chemistry. This work focused on studying the electrochemical properties and electroanalytical application of electrochemical sensors based on reusing industrial or electronic waste in the fabrication, or modification of surfaces. The first step of this work presents an application for carbon nanomaterials synthesized from food industry waste. The nanomaterials were synthesized through exfoliation and thermal reduction methods. r-rGO was characterized by: SEM, XRD, FTIR, and Raman spectroscopy. To evaluate the performance of r-rGO was used drop-casting modification on a GCE (r- rGO/GCE) for electrochemical and electroanalytical testing. The proposed modified sensor was applied in the determination of paracetamol (PAR), linear range of 60 – 500 μmol L-1 and LOD of 0.28 μmol L-1. Then, r-rGO/GCE was used in PAR tablets with recovery rates of 99.7% and 104%. Another class of solid waste of interest in this work was electronic waste (e-waste). This waste comprises various components, including microchips in electronic devices such as computers and smartphones. Microchips often contain valuable materials such as gold, silver, copper, and rare earth elements. However, when these devices become obsolete or stop working, they add to the increasing amount of electronic waste. In this context, it was proposed using microchips (i.e., retired from obsolete or damaged computers) as an inexpensive source of gold microelectrodes arrays (Au-µEA). The morphology and structure were established by optical microscopy, SEM and EDS. A bismuth film was deposited in situ on a gold microelectrode array (BiF/Au-µEA) for the detection of Cd(II) and Pb(II) in water samples. An experimental design (CCD) was applied to evaluate and optimize the effect of the variables that act on the voltammetric response of the analytes studied (deposition time, deposition potential, Bi(III) concentration, acetate buffer pH, amplitude, step potential and frequency). BiF/Au-µEA sensor proved to be appropriate for Cd(II) and Pb(II) detection, exhibited a linear response to Cd(II) 0.5–13 μmol L-1, LOD of 2.56 μmol L-1 and to Pb(II) in the linear range 1.5 – 13 μmol L-1, LOD of 3.40 μmol L-1, which enabled a good recovery of Cd(II) and Pb(II), 114% and 93%, respectively, added to lagoon water. A new method for microchips involved using a nanoporous gold film as an electrochemical sensor (NPG/µEA) to measure isoniazid (INZ). The nanoporous structure was formed through an electrochemical anodization-reduction process, with the advantage of being a simple modification route, without the need for gold precursors or reducing agents. NPG/µEA showed higher electrocatalytic activity for INZ than Au-µEA, with better sensor sensitivity at pH 5.0 in the supporting electrolyte 0.1 M BR. NPG/µEA showed linearity of 10-300 μmol L-1 and a LOD of 1.43 μmol L-1, enabling accurate quantification of INZ in pharmaceutical samples with a recovery result of 102.25%.