Horsey worked for the Russia Company from 1572 to about 1585. He was made an Esquire of the Body to Queen Elizabeth in 1580, was knighted on 23 July 1603 and Receiver of Crown Lands in nine counties in June 1604. He was a Justice of the Peace in Buckinghamshire from about 1601 and High Sheriff of Buckinghamshire in 1611–12. He represented various places, Saltash (1593), Camelford (1597), Bossiney (1601, 1604 and 1614) and East Looe (1621), in Parliament, serving over 30 years. He translated the Slavonic Bible and was responsible for introducing the term "White Russia" into England for Belarus.