Ms King became the first woman to serve as a national officer of SIPTU,the country’s largest trade union, when she was appointed as vice president in May 2010.
From Co Wicklow, she has worked for 25 years as a full time union organiser, representing workers both in the public and private sector.
Ms King was appointed as regional secretary of SIPTU's Dublin region representing some 72,000 members across all sectors, in 2004. She has also served as a member of the RTÉ Authority and the National Roads Authority.
Ms King was prominently involved in the Irish Ferries dispute in 2006/07 and played a central role in the negotiation of employment rights legislation including the establishment of the National Employment Rights Authority.