This paper presents the design of a compact third-order sinusoidal oscillator based on an operational transresistance amplifier (OTRA). The proposed circuit consists of a single OTRA combined with three resistors and three capacitors. Areview of relevant literature revealed that this is the first study to design a third-order sinusoidal oscillator, constructed with a single OTRA and the minimal number of passive components, with independent control of the oscillation condition and frequency. This study involved a review of previous designs as well as related formulations, nonideal analyses, and sensitivity discussions regarding the proposed circuit. Because the proposed circuit features a low-impedance output, it can be applied in cascading and used without additional buffer circuits. This study conducted simulations for the proposed circuit using HSPICE, and used commercially integrated circuits (ICs) and discrete components for circuit implementation and testing to verify its feasibility. Simulation and experimental results confirmed the validity of the proposed oscillator circuit.