Dúnlaing mac Muiredaig (died 869) was a King of Leinster of the Uí Muiredaig sept of the Uí Dúnlainge branch of the Laigin. This sept had their royal seat at Maistiu (Mullaghmast) in South Kildare. He was the son of Muiredach mac Brain (died 818), a previous king. He ruled from 863 to 869. In 868 the annals record that the Laigin participated with the Uí Néill of Brega and Norse at the Battle of Cell Ua nDaigri on the Boyne estuary. They were defeated by the high king Áed Findliath (died 879). Dúnlaing's name is not mentioned with connection to this event.