Ahtisaari is a surname. It may refer to:

• Eeva Ahtisaari (born 1936), Finnish teacher and historian, the First Lady of Finland from 1994 to 2000 married to the 10th President of Finland Martti Ahtisaari
• Marko Ahtisaari (born 1969), Finnish technology entrepreneur and musician
• Martti Ahtisaari (1937–2023), Finnish politician, the tenth President of Finland (1994–2000), a Nobel Peace Prize laureate, and a United Nations diplomat and mediator