Abstract In the past years, high‐quality semiconducting single‐walled carbon nanotube (s‐SWCNT) inks obtained by conjugated polymer wrapping using toluene as solvent have been used for the fabrication of high‐performance field‐effect transistors. Charge‐carrier mobilities up to 50 cm 2 V −1 s −1 and on/off ratios above 10 8 have been reported for devices based on networks of s‐SWCNT. However, devices fabricated from inks that are only a few weeks old generally show a marked decrease in performance, indicating the limited shelf life of toluene‐based inks. The use of o‐xylene as applicator solvent to obtain high quality and very stable s‐SWCNT inks is reported. The charge carrier mobility of field‐effect transistors fabricated with this new ink show a twofold increase in magnitude compared to devices prepared from a toluene solution. More importantly, the device‐to‐device performance shows improved reproducibility, which is ascribed to the higher degree of homogeneity of the s‐SWCNT network deposited from o‐xylene with respect to the one from toluene. Finally, the o‐xylene inks maintain their initial properties for longer than one year. This very long shelf life is an important pre‐condition for the industrial use of s‐SWCNT inks.