The monitoring of vital signs in real time is fundamental to proactive and preventive health care, yet conventional monitoring systems remain expensive, tethered, and limited to single-parameter measurement. This study presents the development, implementation, and performance validation of a low-cost, multi-parameter Wearable Remote Patient Monitoring (WRPM) device capable of simultaneously measuring heart rate (HR), peripheral oxygen saturation (SpO2), and body temperature (Temp). The device was constructed using an ESP32 microcontroller board, a MAX30100 pulse oximeter and heart rate sensor, a DHT11 temperature sensor, and a 0.96-inch OLED display module, powered by a 3.7 V rechargeable lithium-ion battery. Measured data are streamed in real time to the ThingSpeak IoT platform via the ESP32's onboard Wi-Fi module. Performance validation was conducted on n = 20 volunteer adult students (both male and female) recruited by simple random sampling from the School of Science Laboratory Technology, University of Port Harcourt, Rivers State, Nigeria. Measurements obtained from the WRPM device were compared against commercially available reference instruments: a pulse oximeter (for HR and SpO2) and a digital thermometer (for temperature). Statistical analyses included mean ± standard deviation, mean bias, standard deviation of differences, Bland-Altman limits of agreement (LoA), and mean absolute percentage error (MAPE). Results showed mean values of 79.1 ± 8.9 bpm (WRPM) versus 78.6 ± 8.6 bpm (standard) for HR; 96.9 ± 1.2% (WRPM) versus 97.0 ± 1.2% (standard) for SpO2; and 36.74 ± 0.27°C (WRPM) versus 36.84 ± 0.27°C (standard) for temperature. Bias values were +0.50 bpm, −0.10%, and −0.10°C, with MAPE values of 0.67%, 0.10%, and 0.27%, respectively, indicating excellent agreement with reference standards. The developed WRPM device demonstrated accuracy and reliability comparable to commercially available medical devices and represents a viable, affordable solution for multi-parameter remote patient monitoring, particularly in resource-limited healthcare settings in subSaharan Africa.