Hillman joins the World Bank after three years as director of external comms for the Bill & Melinda Gates Foundation and a long career as a BBC journalist.
His move comes as the World Bank, a UN-created institution that provides loans to developing countries, undergoes a major shake-up under President Jim Yong Kim aimed at saving $400m (£247.5m) by 2016.
Hillman, whose arrival follows previous director of corporate comms Richard Mills' departure for The George Institute for Global Health, said: "The bank does incredible work with a huge number of experts across a range of issues, but the challenge is how to tell a strong story about what it does to join up all of its effort in support of all its goals."
Some reports claim more than 1,000 job cuts are likely to take place at the development institution, which is thought to currently employ about 10,000 staff across 120 countries.
However, Hillman pointed to the changes as increasing the focus of the bank on ending extreme poverty by 2030 and building shared prosperity.
"Like most big institutions that are quite complex and do a lot, it’s struggled in the past to tell a strong narrative, but with a new structure and focus there’s a real opportunity to tell that story very clearly.
"Outside of a subset of the development community the bank’s work is not broadly known and understood, so we want to build an understanding of the bank as an institution and its brand.
"It’s about telling the story in a coherent convincing way, whether it’s about our fantastic data, amazing research or deep expertise on a range of topics."
Prior to joining the Bill & Melinda Gates Foundation, a philanthropic group set up by the Microsoft founder, Hillman spent 17 years at the BBC where he was most recently editor of its economics and business centre.