Knutsen Mienna won the Norwegian league with Røa IL in 2007 and 2008, and also in 2008 won the Royal Cup to complete "the double". She helped her club to the double again in 2009, and they won the Cup in 2010 and then the League in 2011.
Knutsen Mienna competed with Norway in the 2008 Summer Olympics in China and scored the opening goal in the group match against Japan. Norway was defeated by Brazil in the quarter-finals.
In October 2008 Knutsen Mienna was one of five Røa players who announced their refusal to play for the national team under the management of Bjarne Berntsen. She was recalled by Berntsen's successor Eli Landsem and was selected for the 2011 FIFA Women's World Cup in Germany. Knutsen Mienna won a total of 36 senior caps and scored three goals for Norway.