Jeffreys was the son of Arthur Jeffreys, member of the New South Wales Legislative Council, who had emigrated to Australia in 1839. During his youth he was a successful cricketer with Hampshire and New South Wales. He was elected to the House of Commons for Basingstoke in 1887, a seat he held until his death, and was admitted to the Privy Council in 1902. He served briefly under Arthur Balfour as Parliamentary Secretary to the Local Government Board from June to December 1905. Jeffreys died in February 1906, aged 57. His son George became a prominent military commander and was elevated to the peerage as Baron Jeffreys in 1952.