Trains run approximately once every hour, traveling the entire length of the line. Some trains travel through onto the Tōhoku Main Line to Utsunomiya Station.
Most services on the line are operated by KiHa 40 series single-car diesel multiple unit (DMU) trains, but from the start of the revised timetable on 15 March 2014, a new EV-E301 series two-car battery electric multiple unit (BEMU) was introduced on the Karasuyama Line and Tohoku Main Line between Utsunomiya and Karasuyama. Developed from the experimental "Smart Denchi-kun" battery electric railcar also tested on this line since 2012, the EV-E301 series train is recharged at a special recharging facility built at Karasuyama Station, and operates on battery power over the non-electrified Karasuyama Line tracks. The intention is to ultimately replace all of the diesel trains used on the line with new EV-E301 series battery electric units.