Easterbrook replaces Steve Hill who stepped down from the role in June.
Wagamama is owned by private equity firm Duke Street Capital. It has become increasingly popular in the UK in recent years.
Easterbook joined McDonald's in 1993 and worked at the fast-food giant for 18 years. In August 2011 he stepped down as president of McDonald's Europe to join Pizza Express as its chief executive, surprising many in the industry.
Wagamama says it has ambitious growth plans. Currently, it operates 84 restaurants globally, with plans to open 15 restaurants a year in the UK.
Wagamama is thought to have big plans to grow overseas, through running a franchise strategy. Easterbook has significant experience in running food franchise operations.Follow @johnreynolds10