In partnership with Manning Gottlieb OMD, the agency will handle a £3 million campaign reinforcing upcoming regulations making disability discrimination an offence alongside racism, sexism and ageism.
HHCL and Manning Gottlieb OMD saw off a challenge from J. Walter Thompson and Naked to capture the business in a pitch that was overseen by COI Communications.
The Department of Work and Pensions is co-ordinating the integrated campaign, which will begin next year to help change attitudes towards the disabled.
Minnie Moll, the HHCL managing partner, said: "We're extremely pleased to be building on our existing COI business, especially on a project that gives us such an exciting opportunity to do some very powerful work for an important issue."