Current mobile revolution is leading to an increase of wearable health devices development and consequently a growth in ambulatory monitoring area. These systems can be applied in ambulatory diseases management and diagnosis, personal health monitoring or sports performance enhancement, providing physiological and body-area ambiance data during daily normal activities. Nowadays several devices in the market have this type of technology, being one of them the VitalJacket® (VJ®), a product from Biodevices, S.A. This device is a medical certified smart t-shirt with textile embedded electronics for ambulatory monitoring of electrocardiogram (ECG), Heart Rate (HR) and Accelerometer (Acc) data that is in the market since 2008. In this work we report the result of a university-company joint R&D effort that aimed to propose a reference extension architecture – called VitalLogger – for VJ® wearable health device that enables sensors seamless plug-in to the company product. As a proof of concept of this novel adaptable architecture, we jointly implemented a prototype that extends VJ® technology to incorporate new sensing modules in a seamless way. Both hardware and firmware were re-designed and extended to create a reference extension architecture, enabling easy integration of different sensing modules according to the user monitoring preference/scenario. Besides the ECG module already incorporated in VJ®, a module with a Blood Oxygen Saturation (SpO2) sensor and an ambiance temperature and relative humidity sensor was developed and added to the extended prototype VitalLogger. This prototype was successfully built and tested, showing excellent results. The VitalLogger adaptable extension architecture has shown its scalability by enabling seamless plug-in sensing modules thus creating the possibility of swift creations of new products with different sensors combinations to adapt to different monitoring scenarios.