Gelli is a small settlement in the community and parish of Llawhaden, Pembrokeshire, Wales, at the confluence of the Syfynwy and Cleddau Ddu rivers. It is 3 miles (5 km) northwest of Narberth and 8 miles (13 km) east of Haverfordwest. The nearest railway station is at Clunderwen 2 miles (3 km) to the east. There was a woollen mill in Gelli that ceased production in 1938.