Kristjánsson is a surname of Icelandic origin, meaning son of Kristján. In Icelandic names, the name is not strictly a surname, but a patronymic. Notable people with the surname include:
- Albert Kristjansson (1877–1974), Canadian politician from Manitoba; provincial legislator 1920–1922
- Benedikt Kristjánsson (born 1987), Icelandic tenor
- Broddi Kristjansson (born 1960), Icelandic Olympic badminton player
- Guðjón Arnar Kristjánsson (1944–2018), Icelandic politician; member of the Alþing since 1999
- Jón Kristjánsson (1920–1996), Icelandic Olympic cross-country skier
- Jónas Kristjánsson (1924–2014), Icelandic scholar and novelist
- Matthías Kristjánsson (1924–1998), Icelandic Olympic cross-country skier
- Sigurður Kári Kristjánsson (born 1973), Icelandic politician; member of the Alþing since 2003
- Snorri Hergill Kristjánsson (born 1974), Icelandic author
- Stefán Kristjánsson (1982–2018), Icelandic chess grandmaster