Thermotolerant Campylobacter bacteria, most notably Campylobacter jejuni and Campylobacter coli, are a major cause of human foodborne gastroenteritis, which is usually related to consumption of contaminated poultry. In this work, we present a sensor and the associated assay for the on-site detection of the prevalent species C. jejuni and C. coli. The sensor uses surface-imprinted polymer (SIP) layers as selective, biomimetic recognition elements in combination with a modified heat-transfer method (M-HTM) as a label-free, quantitative readout principle. The selectivity for C. coli and C. jejuni was evaluated against six other morphologically similar Campylobacterales species, confirming that the sensor is selective at species level while responding uniformly to different strains within the same species. For the relevant matrix, that is chicken cecal droppings suspended in PBS buffer, the detection limits are 1.1 × 103 CFU/mL for C. coli and 2.7 × 104 CFU/mL for C. jejuni, which is both low enough for a meaningful diagnostic test. The sensor concept requires only a minimum of sample preparation and a given concentration can be measured within less than one hour: Both are important assets for on-site detection such as on a poultry farm or in a slaughterhouse, keeping in mind that Campylobacter detection with established methods in analytical laboratories takes 2–4 days for obtaining the result.