The company, whose chief executive Ho Ching is the wife of Singapore's prime minister, has made over its image in the past several years, helping to diminish a reputation for secrecy and lack of public accountability.
Zoellick is Temasek's highest profile board appointment.
An earlier attempt to attract international talent backfired. Former BHP Billiton boss Chip Goodyear was recruited as CEO in 2009 but backed out before his appointment took effect because of differences over investment strategy.
Temasek is working on setting up its first office in the US. It says its investments were worth 215 billion Singapore dollars (USD 169 billion) at the end of March. The bulk of Temasek's money is invested in Asia.