Before there was Aon Hewitt, there were two companies: Aon and Hewitt. The former was a leading provider of risk management and insurance services, while the latter was a specialist HR consulting outfit. When the former purchased the latter for  around $4.9 billion in 2010, the Aon brand and business lived on, with one important addition: the subsidiary firm of Aon Hewitt, under whose aegis the firm's HR consulting operations are now grouped. 

According to the firm's most recent annual report, the Aon Hewitt unit generates around one third of Aon's total revenue, and "works to maximize the value of clients’ human resources spending, increase employee productivity, and improve employee performance. Our approach addresses a trend towards more diverse workforces (demographics, nationalities, cultures and work/lifestyle preferences) that require more choices and flexibility among employers — so that they can provide benefit options suited to individual needs."