Dyfed-Powys Police attended a property in the Pontyglasier area, near Crymych, following reports of a house fire at shortly before 10pm on Saturday, 27 May.
Mid and West Wales Fire and Rescue Service, The Welsh Ambulance Service and the Welsh Air Ambulance attended also attended.
Despite the efforts of emergency services, five-year-old Alysia Salisbury died at the scene.
Alysia’s family, who have described her as “a beautiful daughter and sister”, are being supported by specialist officers.
DCI Llyr Williams said: “Our thoughts are with the family and the local community at this tragic time. HM Coroner has been informed and officers will now work with colleagues form the fire service to establish the cause of the fire.
“The family request privacy at this difficult time”
The operation saw fire crews from Crymych, Cardigan, Newcastle Emlyn, Whitland and Fishguard in attendance, with specialist kit a turntable ladder from Haverfordwest, a water bowser from Milford Haven and the Urban Search and Rescue Team in attendance.