Lyngdalsfjorden is a fjord in Agder county, Norway. The 16-kilometre (9.9 mi) fjord begins at the village of Alleen in Lyngdal municipality and it flows southwest into Farsund municipality before emptying into the North Sea just south of the town of Farsund. The 1-to-2-kilometre (0.62 to 1.24 mi) wide fjord is fed by the river Lygna at Alleen and it has a couple larger fjords that join the Lyngdalsfjorden. The Åptafjorden joins the Lyngdalsfjorden from the northwest, coming from Sande and Åpta in the Herad area. The large lake Framvaren flows into the Helvikfjorden, which joins the Lyngdalsfjorden from the west.

• List of Norwegian fjords