Ulla Marianna Väistö (born 1948) is Finnish diplomat. She is serving as Finland's ambassador to Romania at the Embassy of Bucharest since September 2011. She is also an Ambassador to Moldova from Bucharest. Between 2007 and 2011, Väistö was the ambassador to Mexico, Belize, Haiti and Cuba. By education she is a Master of Science in Economics.
Väistö entered the Ministry for Foreign Affairs in 1976. She has worked in embassies in Brussels, Vienna, Bonn and Paris and in Strasbourg at the Finnish Permanent Representation. In the Ministry she was Head of the Administrative Department from 2004 to 2007 and from 2001 to 2004 Director of Human Resources.[1]