Spencer was the son of Sir John Spencer (died 1586) of Althorp, Northamptonshire, and his wife Katherine Kitson, daughter of Sir Thomas Kitson of Hengrave, Suffolk.

Educated at Trinity College, Cambridge, he then trained in the law at the Middle Temple.

He succeeded his father in 1586, inheriting estates at Wormleighton, Warwickshire, and Althorp, Northamptonshire, and was knighted in 1588.

His monument was made by Joseph Hollemans, a Dutch sculptor residing in Burton-on-Trent.

[1] Spencer married Mary Catlyn, the only daughter and heiress of Sir Robert Catlin, who brought him estates in both Leicestershire and Northamptonshire.