Hydrocarbon leakages are incredibly prominent in today's oil and gas transportation infrastructure, causing several billion dollars of environmental damage annually. Mitigation of this issue is primarily carried out via leak detection sensor systems using fiber optics cables, which are highly prone to failure but are conventionally utilized in industry due to a lack of commercially feasible alternatives. Likewise, sensor solutions in literature have also proven infeasible, featuring high accuracies coupled with difficulties in technology scale-up. Herein we develop a unique hydrocarbon sensor with both scalability and accuracy, using hydrocarbon-soluble polymers in composite chemiresistive sensors. The design's novelty is based on the simple yet highly potent effects of dissolution that take place after exposure to aromatic elements of hydrocarbons pollutants. Large structural deformations are caused in the sensor and can be detected quickly and accurately. In this study, four soluble polymers are characterized for hydrocarbon susceptibility via crude oil exposure, and show large changes in physical and rheological properties. Large electrical sensor response magnitudes are achieved, of up to 180% in 1 h and 27555% in 6 h. Overall, high efficacy in hydrocarbon leak detection is achieved, validating the sensing effectiveness of this unique, hydrocarbon-soluble polymer-based design.