Born in Umnäs, Gideonsson moved around Sweden with her family until they settled in Lycksele in the northern part of the country.
She worked part-time delivering newspapers from the age of 14, when she joined the Swedish Transport Workers' Union.
At the age of sixteen, she began working in the local woodworking factory, and in 1983, she was elected as leader of the joint committee of Swedish Trade Union Confederation (LO) affiliated unions in the town.
After the factory was sold, she was unemployed for a period before finding work with the forestry service.
As leader, she proposed to focus on strengthening the trade union movement, reduce exploitation at work, promote equality and campaign for strong social welfare.