Walters takes on the role a year after being made redundant from GCI, where he acted as chief executive of the Hong Kong office alongside his responsibilities as regional chairman.
His role was axed following Grey Advertising's decision to merge the Asian operations of GCI and sister agency APCO Worldwide.
Moravick returns to New York next month after just over a year in the post, which she oversaw on an interim basis alongside her role as head of MS&L's healthcare practice and member of the office of chairman Louis Capozzi.
In New York, Moravick will concentrate on her healthcare responsibilities and on developing the network's planning and evaluation tools.
Walters said there are no plans to make any drastic changes in the London division, but added there would be areas for concentration.
'MS&L has an enviable position in healthcare and is strong in consumer, but we would like to build up our strength in the areas of corporate and B2B,' said Walters.