This fatal road incident happened in the Fortunestown Lane area last night at around 10.30pm.
A male cyclist - aged in his late teen - was seriously injured when he hit a pillar in a residential area.
Emergency services rushed to the scene and the man was taken to Tallaght Hospital where he was later pronounced deceased.
No other vehicles were involved in the accident.
A technical examination of the scene was carried out by Gardai and they are appealing for witnesses.
They particularly want to speak with anyone who was in the vicinity of Mac Uilliam Heights yesterday evening between 10pm and 10.45pm and who may have camera or dashcam footage
Anyone with any information is asked to contact Tallaght Garda station on 01 666 6000.
