Wilhelmsfehn I is a district (Stadtteil) of the East Frisian town of Wiesmoor, in Lower Saxony.

A linear settlement, it is located northwest of the town, to the north of Wilhelmsfehn II.

The moor colony was founded in 1888 as an eastern extension of Ostgroßefehn and is still closely linked to it in terms of urban development today: the transition is fluid.

The village was created by the Großefehngesellschaft and was named after Emperor Wilhelm I.

By 1921 the town had grown to 245 inhabitants.