Gosnold was born in Grundisburgh in Suffolk, England in 1571, and his family seat was at Otley, Suffolk. His parents were Anthony Gosnold of Grundisburgh and Dorothy Bacon of Hessett. Henry Gosnold, the judge and friend of Francis Bacon, was his cousin. Bartholomew had a younger brother Anthony, born sometime between 1573 and 1578, who accompanied him to Virginia as well as a cousin also named Anthony Gosnold who was alive and still living in Virginia in 1615. In 1578, the will of Bartholomew's great-grandmother Ann Doggett (Bacon) Gosnold shows five sisters to Bartholomew and Anthony.