Vallance, who will be based out of HGS' European headquarters in West London, will work on driving growth in the region and further enhance its scope of services, HGS said in a statement.
He has over 20 years of global outsourcing experience across BFSI, telecom and media industry segments, it added.
Vallance joins HGS from Sutherland Global Services, where he held the role of MD for Europe and emerging markets.
He has also been associated with Firstsource Solutions, where he spearheaded the creation of the company's European business. He has also been an entrepreneur, having founded sourcing advisory business, InCode in 1998 and been part of Customer Asset's founding team.