Carbyne and linear carbon structures based on sp-hybridization are attractive targets as the ultimate 1D system (i.e., one-atom in diameter) featuring wide tunability of optical and electronic properties.1–3 Two possible structures exist for sp-carbon atomic wires a) the polyynes with alternated single-triple bonds, and b) the cumulenes with contiguous double bonds. Theoretical studies predict semiconducting behaviour for polyynes, while cumulenes are expected to be metallic. Very limited experimental work, however, has been directed toward investigating the electronic properties of these structures, mostly at single molecule or monolayer level.4–7 Yet, sp-carbon atomic wires hold great potential for solution-processed thin film electronics, an avenue not yet exploited to date. Herein, we report the first field-effect transistor (FET) fabricated employing cumulenic sp-carbon atomic wires as a semiconductor material. Our proof-of-concept FET device is easily fabricated by solution drop casting and paves the way for exploiting sp-carbon atomic wires as active electronic materials.