Salicylic acid (SA) is a primary phytohormone released in response to stress, particularly biotic infections in plants. Monitoring SA levels may provide a way for early disease detection in crops providing a way for applying effective measures for reducing agricultural losses while increase our agricultural efficiency. Additionally, SA is an important chemical used extensively in the pharmaceutical and healthcare industry due to its analgesic and anti-inflammatory properties. Developing a fast and accurate way for monitoring SA levels in human serum can have a life-saving impact for patients suffering from overdosing and/or mis-dosing. In this work, we present a low-cost, portable, and field-deployable electrochemical SA sensing system aimed towards achieving the above-mentioned goals. The developed sensor consists of a plugand-play type device equipped with specialized designed high accuracy sensing electronics and a novel procedure for robust data analysis. The developed sensor exhibits excellent linearity and sensitivity and selectivity. The practical applicability of the developed sensor was also demonstrated by measuring SA levels in real samples with good accuracy.