The sit-to-stand (STS) movement is a common activity essential for independence and mobility. Traditional methods for assessing STS often involve costly laboratory equipment, limiting their accessibility. This study introduced an economic alternative to the standard motion capture setup. The system presented in this study used an Azure Kinect and a plantar pressure sensor mat to acquire kinematic and kinetic data simultaneously during the STS. The Kinect provided non-contact motion capture, while the pressure sensor array measured ground reaction forces. To address the Kinect's inherent limitations in capturing extremity movements and the sensor array's inability to measure tangential forces, algorithms for the correction of lower limb joints and a multisource fusion model were developed. The accuracy of the proposed system was evaluated against a gold standard Vicon motion capture system. The results indicated that the system delivered estimates comparable to reference values for joint angles (r ranging from 0.85 to 0.99), antero-posterior and vertical ground reaction forces (r ranging from 0.81 to 0.98), joint reaction forces of knee and ankle (r ranging from 0.83 to 0.90), and joint moments of hip and ankle (r ranging from 0.77 to 0.82), suggesting that the proposed system can provide vital kinematic and kinetic data for efficient STS analysis. This study offered an accessible and practical solution for monitoring and assessing mobility in various settings.