Clynnog Fawr lies on the A499 road between Caernarfon and Pwllheli, at grid reference SH415500, between the coast and a mountainous area including Bwlch Mawr.

Clynnog means 'the place of the holly-trees': compare Breton Quelneuc (Kelenneg), Gaelic Cuilneach.

[3] It developed into an important foundation and some Welsh law manuscripts specify that the Abbot of Clynnog was entitled to a seat at the court of the king of Gwynedd.

The area has been the site of a number of battles, including the Battle of Bron yr Erw in 1075 when Gruffudd ap Cynan's first bid to become king of Gwynedd was defeated by Trahaearn ap Caradog, and the Battle of Bryn Derwin in 1255 when Llywelyn ap Gruffudd defeated his brothers Owain and Dafydd to become sole ruler of Gwynedd.

Clynnog is covered by a Neighbourhood Policing Team based in the nearby village of Penygroes.