The collision happened on the N69 close to Dromin Upper shortly after 3am. The teenager was pronounced dead at the scene, and gardaí say the van did not stop.
Officers later traced the vehicle and arrested a man in his 30s in connection with the incident. He is being held under Section 4 of the Criminal Justice Act 1984 at a Garda station in Kerry.
The stretch of the N69 between Cahirdown Roundabout and Derry, both in Listowel, remains closed while a technical examination takes place, with diversions set up locally.
Gardaí are appealing to anyone who was in the area of the N69 near Dromin Upper between 2.30am and 4am to come forward, particularly if they have relevant footage, including from dash-cams.
Witnesses or anyone with information can contact Listowel Garda Station at 068-50820, the Garda Confidential Line on 1800 666 111, or their nearest Garda station.
