A low-temperature hydrothermal method was used to synthesize a unique parallelogram (Pg) morphology based on Pg-NiFe₂O₄ and Pg-NiFe₂O₄/reduced graphene oxide (rGO) nanocomposite. This unique Pg morphology provided high surface area, loading of a biomolecule, and high charge transfer between the substrate and analyte. This nanocomposite enabled creation of an efficient selective electrochemical biosensor for 3,4-dihydroxy phenylalanine (dopamine (DA)). DA is a key monoamine neurotransmitter that causes numerous disorders, including Parkinson's disease, Alzheimer's disease, dementia, and hyperactivity disorder due to an imbalanced concentration of DA in biological fluids. Thus, the in situ-prepared Pg-NiFe₂O₄/rGO nanocomposite was utilized for immobilization of the enzyme tyrosinase (Tyr) and for electrochemical estimation of DA. In addition, the structural, morphological, and electrochemical characteristics of the synthesized Pg nanocomposite were investigated by X-ray diffraction analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, UV-visible spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and electrochemical method. The Tyr/Pg-NiFe₂O₄/rGO/ITO bioelectrode had a excellent linear detection range of 1–300 μM, high sensitivity (9.456 × 10⁻⁴ mA μM⁻¹ cm⁻²), low response time of 10 s, long stability of 40 days, good repeatability, and low limit of detection (0.0456 μM). Hence, the in situ-prepared nanocomposite, with its unique parallelogram morphology, offers an efficient means for monitoring DA, that can be essential for managing neurodegenerative disorders, by providing excellent sensitivity, stability, and detection capabilities.