Royal HaskoningDHV was formerly known as SSI Engineers and Environmental Consultants, and was founded in Johannesburg, South Africa in 1922. Registered as Stewart Scott (Pty) Ltd and trading as Stewart Scott International (SSI), the company owes its name to its founding fathers – George Stewart, a specialist in water cycle and municipal services projects and Frederick Scott, whose forté was transport and structural design. An innovator from its early years, SSI was one of the very first independent consulting engineering companies in Southern Africa and later, also one of the first to be established as an empowerment company.
The company's name changed to SSI, a DHV company, in September 2006 after the DHV Group became the majority shareholder. Following the merger between DHV and Royal Haskoning in 2012, the company changed its name to reflect the international branding of the enlarged group.