He was the second son of Peter FitzHerbert and Alice de Warkworth, and following the death of his brother inherited the minor Marcher Lordship of Blaenllynfi from him.

FitzPiers was the second son of Peter FitzHerbert and Alice de Warkworth.

During 1261, FitzPiers was made sheriff of Hampshire, and governor of Winchester Castle.

In 1282, he participated in the campaign of King Edward I of England in Wales against Llywelyn ap Gruffudd.

Fitzpiers first wife was Alice, daughter and heir of William de Standford, they had the following known children: After de Standford's death Fitzpier married Joan, daughter and coheir of William de Vivonia and Maud de Ferrers, they had the following known children: