Strutt was born on 12 November 1842 at Langford Grove in Maldon, Essex. In his early years he suffered from frailty and poor health. He attended Harrow School, before going on to the University of Cambridge in 1861 where he studied mathematics at Trinity College, Cambridge. He obtained a Bachelor of Arts degree (Senior Wrangler and 1st Smith's prize) in 1865, and a Master of Arts in 1868. He was subsequently elected to a Fellowship of Trinity. He held the post until his marriage to Evelyn Balfour, daughter of James Maitland Balfour, in 1871. He had three sons with her. In 1873, on the death of his father, John Strutt, 2nd Baron Rayleigh, he inherited the Barony of Rayleigh.