His father, Pedro Theon [pt] (d. after 867), sometimes called Pedro Theón of Pravia, and possibly the son of Bermudo I of Asturias, was a member of the Curia Regis of King Alfonso III and appears in January 867 confirming a royal charter jointly with other nobles, including Count Rodrigo of Castile.

Vímara was a vassal of the King of Asturias, Alfonso III, and was sent to reconquer and secure from the Moors (Arabs and Berbers who had invaded Visigothic Hispania), in the west coastal fringe of Gallaecia, the area from the Minho River to the Douro River, including the city of Portus Cale, later Porto and Gaia, from where the name of Portugal emerged.

In 868, Vímara Peres was named Count of Portugal by King Alfonso III after the reconquest of the region north of the Douro river.

He was able to expel the Moors and founded a fortified town under his own name Vimaranis (of Vimar) which later became Guimaranis, present-day Guimarães (the Portuguese call it "The Cradle City").

Vímara Peres died in 873 in Vama, possibly identified as Guimarães or Bama in the territory of Touro, A Coruña.