Temperature is the extent of the coldness or hotness materials. It is a basic physical quantity which affects any object and process like industrial processes, electrical systems’ components, life and health of living things, agricultural soil, bridges, highways, buildings, dams, environment, etc. So, it should be properly measured and regulated using greatly accurate, precise, environmentally friendly, in-situ, low-power and low cost thermometers. There are plenty of thermometers with the drawbacks of high power consumption, possession of toxic materials, costly, less accurate and imprecise. In this work, I discuss the design and development of a nanoceramic nickel manganate (NiMn2O4) thermistor powder-based digital electronic thermometer probe. The nanomaterial was synthesized using acetates of Nickel (Ni) and Manganese (Mn) as precursor materials by using the wet chemical method. The fabricated powder was characterized using field emission scanning electronic microscopy (FeSEM) and energy dispersive spectroscopy (EDS) for its morphology and composition respectively. Powder x-ray diffraction (XRD) was also used to determine the crystal structure and crystallite size of the sample. The sample is unform in morphology, spinel in structure, 24 nm in average crystallite size and composed of Ni, Mn and O2 in the proper ratio. The 0.35 g of the powder was filled and pressed well in a 2 mm diameter and 2 cm long cylindrical tube to fabricate and characterize the thermistor-based thermometer. The resulting thermistor was characterized and calibrated using the Stein and Hart and the β-coefficient thermistor calibration modelling techniques. The embedded system was also developed using atmega328 microprocessor-based microcontroller, a simple signal conditioning electric circuit, stainless steel cylindrical tube and 3D printed package. The system was programmed using Arduino programming integrated development environment. The features of the resulting thermometer are 4-digit precision, 0 °C–70 °C range of temperature measurement, 5 V DC power supply requirement, contains environmental friendly chemicals and is highly accurate. It can be used primarily in agriculture. It can also be used in industry, medicine, automobile, environment, food processing, home automation, etc. Additionally, this thermometer can also be used as the element of sensor nodes in wireless sensor networks (WSNs) and Internet of Things (IoT) technology in automation.