[2][3] Prehistoric people lived in the area in scattered groups of circular huts near the river, Afon Crawcwellt, about two miles south of today's village.

[4] By the early medieval period, the village was part of a large Celtic Christian parish of the three settlements of Trawsfynydd, Prysor, and Cefn Clawdd.

Records in the Meirionnydd Lay Subsidy Rolls show that following the English conquest of Wales there were 105 taxpayers in the parish in 1292–3.

In the late 16th century, the parish of Trawsfynydd was home to Saint John Roberts, one of the Forty Martyrs of England and Wales (he was canonised in 1970).

Between 1924 and 1928, a large man-made reservoir named Llyn Trawsfynydd was created to supply water for Maentwrog hydro-electric power station.

This would lead to the largest change to the village, when a location nearby was chosen as a site for one of the UK's first nuclear power stations in the 1950s.

The lake was subsequently also used to supply cooling water to the twin reactor Trawsfynydd nuclear power station, which was used for the commercial generation of electricity for the UK national grid.

[5] One of the four original dams built to create the lake was subsequently rebuilt after construction of the nuclear power plant.

[6] Trawsfynydd used to be served by a section of the Great Western Railway branch line, which ran from Bala to Blaenau Ffestiniog.

Hedd Wyn is buried with others from his regiment, the Royal Welch Fusiliers, at Artillery Wood Cemetery, Boezinge in Flanders.