Mortensson is a surname, a cognate of Martins (surname). Notable people with the name include:
Daniel Mortensson, early 20th-century Sami activist Ivar Mortensson-Egnund (1837-1954), Norwegian writer and anarchist Jacob Mortenssøn Maschius (1630-1678), Norwegian clergyman and poet Marja Mortensson (born 1995), South Sami singer from Norway