Martin joined IBM in 1959, and since the 1980s established several IT consultancy firms. Starting in 1981 with Dixon Doll and Tony Carter he established DMW (Doll Martin Worldwide) in London, UK, which was later renamed James Martin Associates (JMA), which was (partly) bought by Texas Instruments Software in 1991. He later co-founded Database Design Inc. (DDI), in Ann Arbor, Michigan, to promulgate his database design techniques and to develop tools to help implement them. After becoming the market leader in information technology engineering software, DDI was renamed KnowledgeWare and eventually purchased by Fran Tarkenton, who took it public.