Niemi is a Finnish surname of Laine type literally meaning "peninsula".
- Antti Niemi (footballer) (born 1972), Finnish football goalkeeper
- Antti Niemi (ice hockey) (born 1983), Finnish ice hockey goaltender
- Antti-Jussi Niemi (born 1977), Finnish ice hockey defenceman
- Erkki Niemi (born 1962), Finnish high jumper
- Esko Niemi (1934–2013), Finnish ice hockey player
- Jari Niemi (born 1977), Finnish footballer
- Kai Niemi (born 1955), motorcycle speedway rider
- Laurie Niemi (1925–1968), American footballer
- Lisa Niemi (born 1956), Finnish-American actress and dancer
- Masa Niemi (1914–1960), Finnish actor
- Matti Niemi (rowing) (born 1937), Finnish coxswain
- Matti Niemi (athlete) (born 1976), Finnish hurdler
- Mikael Niemi (born 1959), Swedish author
- Mikko Niemi (basketball) (born 1985), Finnish basketball player
- Mikko Niemi (ice hockey) (born 1972), Finnish ice hockey player
- Pekka Niemi (skier) (1909–1993), Finnish cross-country skier
- Pekka Niemi (weightlifter) (born 1952), Finnish weightlifter
- Pentti Niemi, (1902–1962), Finnish Lutheran clergyman and politician
- Reino Niemi, (1914–1966), Finnish chess player
- Robert Niemi (1955–2022), American literary scholar, literary critic and author
- Shane Niemi (born 1978), Canadian sprints athlete
- Veijo Niemi, Finnish politician
- Virpi Niemi (born 1966), Finnish cross country skier