ABSTRACT Oil spills due to either accidents or deliberate oily discharges cause severe pollution and can be thwarted if proper detection facilities are applied. This article reports new flexible oil sensor capabilities of three different elastomer (natural rubber, butyl rubber, and styrene–isoprene–styrene copolymer) composites of multiwalled carbon nanotubes (MWCNTs). We highlight the sensor manufacturing by simple means of solution mixing, and the uniform dispersion of MWCNTs in the elastomers is substantiated with the help of morphology and structural analyses. Electrical percolation and semiconductor characteristics were also examined for composites. The developed materials show better oil sensing above the percolation level, and the filler–polymer interfacial interaction is the main factor regulating the oil-detecting capability. The efficiency of the sensors was also tested after many instances of bending.