 A native of Ashwellthorpe in Norfolk, Knyvett married Muriel Parry, daughter of Sir Thomas Parry, Comptroller of the Household to Queen Elizabeth I.He inherited the Ashwellthorpe estates from his paternal grandmother, Jane Knyvett ("née" Bourchier), "de jure" 3rd Baroness Berners (daughter and heiress of John Bourchier, 2nd Baron Berners), on her death in 1561/2, along with rights to the title Baron Berners.He was knighted in 1578 and created Lord High Sheriff of Norfolk in 1579.