Lim will assume his post on August 12, said the Foreign Ministry in a statement.
He will replace Karen Tan, who has been appointed as Singapore's Permanent Representative for the United Nations.
Lim was Singapore's Ambassador to Vietnam from 2005 to 2008 and served as Singapore's Permanent Representative to the Association of South East Asian Nations (ASEAN) in 2009.
He holds a Bachelor of Law (Honours) degree from the National University of Singapore and a Master of Arts in Area Studies on South East Asia from the School of Oriental & African Studies at the University of London, the UK.