Geertsen is Danish patronymic surname from the given name Geert. Notable people with the surname include:

• Christopher Geertsen (born 1993), Danish footballer

• Ib Geertsen (1919–2009), Danish painter and sculptor

• Martin Geertsen (born 1970), Danish politician

• Mason Geertsen (born 1995), Canadian ice hockey player

• Nicolai Geertsen (born 1991), Danish footballer

See also