In addition to Önnereds HK, 11 other teams from 6 different countries played in Girls 21. They were divided into 2 different groups, whereof Önnereds HK could be found in Group 2 together with Hyderabad HC, Skåre HK, Torslanda HK 1, Enköpings HF and Hebraica. Önnereds HK made it to A-Play-off after reaching 1:st place in Group 2. Once in the playoff they won every match inluding the Final against IK Sävehof, which they won with 17-15. Thereby Önnereds HK won the entire A-Play-off in Girls 21 during Partille Cup 2013.