The 40-year-old will work with BHA chairman Paul Roy when the new body assumes the roles of the British Horseracing Board and Horseracing Regulatory Authority.
The search for a chief executive had been within racing but Coward's capabilities swung the appointment panel and the industry organisations which had a veto.
Martin Broughton, a member of the panel and chairman of the BHB, explained: "We entered the recruitment process for BHA's chief executive believing that an individual from within the sport was preferable, but Nic's enthusiastic approach towards the issues in racing, allied with his extensive experience in sports administration meant that he soon emerged as the exceptional candidate for the role."
Coward joined the Football Association as its first solicitor from Freshfields, becoming corporate and legal affairs director and then spent almost two years as joint acting chief executive officer. He left in 2004 to join AS Biss & Co., a public affairs consultancy.
He faces many challenges, notably trying to do make sure the new body is more effective than its main predecessor, the BHB.
Coward said: "This is a hugely exciting time for racing. The industry has come together to put in place new structures that will enable it to address the challenges and opportunities that lie ahead.
"I am looking forward to working with Paul Roy, the Board, staff and all the organisations that together create the sport, to bring the BHA to life and deliver the best for British Racing."
Roy added: "Nic has a highly successful track record at the FA. He has wide experience in both governance and regulation and is an independent, strategic thinker who will help to establish swiftly BHA's identity. I am very much looking forward to working with him."