The increase in solid waste generation demands the search for solutions contributing to responsible waste management, minimizing environmental impact, and adding value to these materials. Several strategies can be employed in using these waste materials, including manufacturing low-cost electrochemical sensors. This work focused on developing sustainable electrochemical sensors through the reuse of solid waste for the quantification of the paracetamol and isoniazid in pharmaceutical formulations, heavy metals lead and cadmium in aqueous media. Two main approaches were explored: using carbon nanomaterials obtained from food industry waste and microchips from electronic waste. In the first approach, reduced graphene oxide (r-rGO) was synthesized and used to modify a glassy carbon electrode (r-rGO/GCE), applied in the determination of paracetamol with recovery rates of the active ingredient within the established limits for quality control. In the second approach, microchips were employed in the fabrication of an array of gold microelectrodes (Au-µEA), modified with a bismuth film (BiF/Au-µEA), and applied in the detection of Cd(II) and Pb(II), with evaluation and optimization of the effects of variables that influence the voltammetric response through experimental designs. The findings demonstrated that the developed sensor proved to be suitable for the detection of Cd(II) and Pb(II), exhibiting a linear response for Cd(II) in the range of 0.5 to 13 µmol L−1 and for Pb(II) in the range of 1.5 to 13 µmol L−1. A third approach involved the modification of the microchip surface with nanoporous gold structures (NPG/µEA) to quantify the drug isoniazid. The modified sensor showed higher electrocatalytic activity than conventional gold microelectrodes, enabling the quantification of the analyte in the range of 10 to 300 µmol L−1. Thus, the employed electroanalytical methodologies demonstrated the feasibility of developing electrochemical sensors through the reuse of solid waste. These sensors contribute to waste reduction, more efficient resource utilization, and the promotion of a sustainable approach in the manufacturing of analytical devices.