Mauritz Andersson had the following finishes at major championships – 1907 Unofficial European Championships (5th), 1909 Unofficial European Championship: Unlimited Greco-Roman (4th), 1911 Unofficial World Championships in Helsinki (8th). At the 1908 Olympic Games in London, he achieved his greatest success by winning silver in the middleweight class of Greco-Roman wrestling. He advanced to the final round after winning four bouts, two each by fall and by decision. The final was postponed by one day, to allow fellow countryman Frithiof Mårtensson to recover from an injury. Eventually, Andersson lost the two bouts against Mårtensson, one by decision and one by fall after 6:25 min. In 1912, he was less fortunate although he started the tournament with two victories by fall. He was eliminated, however, after losing to Fridolf Lundsten from Finland in round three.
Andersson joined his club Örgryte IS in 1904. He won the Swedish Championship in 1909 in the heavyweight and one year later in the middleweight B. He worked as an inspector for the Göteborg district chamber.