| Gwaun y Llwyni | |
| Elevation M: | 685 |
| Prominence M: | 43 |
| Parent Peak: | Aran Fawddwy |
| Listing: | Hewitt, Nuttall |
| Language: | Welsh |
| Location: | Gwynedd, Wales |
| Range: | Snowdonia |
| Grid Ref Uk: | SH 85720 20484 |
| Topo: | OS Landranger 124 |
Gwaun y Llwyni is a subsidiary summit of Aran Fawddwy in southern Snowdonia, Wales. It forms a part of the Aran mountain range.
The peak's southern face is very steep and forms one of the backwalls of Cwm Cywarch. The summit is grassy and is marked by a small cairn. Pen yr Allt Uchaf rises on the other side of Cwm Cywarch, Aran Fawddwy is to the north-east, Waun Camddwr to the north and Glasgwm to the west.[1]