Weltzien is a surname. Notable people with the surname include:
Audun Weltzien (born 1983), Norwegian orienteering competitor Eystein Weltzien (born 1949), Norwegian orienteering competitor Ingunn Hultgreen Weltzien (born 1986), Norwegian orienteering competitor and cross-country skier Karl Weltzien (1813–1870), German scientist Ludwig von Weltzien (1815–1870), Prussian lieutenant general