<p>Printed transistors have a wide range of applications, but the limited resolution of printing techniques (10–30 µm) has been a barrier to utility and scalability. Printed submicrometre channel lengths have previously been achieved. However, this has required chemical processes or tedious post-processing, which limits applicability. Here we show that capillary flow printing can create submicrometre carbon nanotube thin-film transistors without chemical modification or physical manipulation after printing. We show that the approach can be used to print conducting, semiconducting and insulating inks on different types of substrate (silicon, Kapton and paper), and can be used to fabricate various thin-film transistor device architectures. The printed carbon nanotube thin-film transistors exhibit on-currents of 1.12 mA mm⁻¹ when back gated on Si/SiO₂ and 490 µA mm⁻¹ when side gated through ion gel on Kapton. We also show that devices printed on Kapton offer mechanical bending and sweep rate resilience, illustrating the potential of these printed devices for flexible applications.</p>