A blue Citroen C3 hit a house near the Conrah Hotel on the A487 in Chancery at about 02:15 BST on Friday.
Firefighters had to cut three people free from the wreckage - one suffered minor injures, two serious.
Dyfed-Powys Police said the house was considerably damaged in the crash and a 24-year-old man has been arrested on suspicion of dangerous driving.
The road was closed for about three hours.
Three people have been injured, two seriously, after a car crashed into a house in Ceredigion.