Joensuu is a Finnish surname. Notable people with the surname include:
Jasmi Joensuu (born 1996), Finnish cross-country skier
Jesse Joensuu (born 1987), Finnish ice hockey player
Jouni Joensuu (born 1962), Finnish association football manager
Matti Yrjänä Joensuu (1948–2011), Finnish writer
Timo Joensuu (born 1959), Finnish oncologist