Ridgeway was born in Macksville, New South Wales, as one of the Gumbaynggirr people. After leaving school in Year 11, he worked as a boilermaker. He then became involved in the public service. In this role, he engaged in a number of careers, including being a park ranger and working in several New South Wales government departments.
In 1990, Ridgeway was elected onto the first ATSIC Sydney Regional Council, a position in which he served two terms of office. He joined the Australian Democrats in 1991. In 1995, he became the executive director of the New South Wales Aboriginal Land Council. He continued in this position until 2000.
During 1997-98 Ridgeway served as the state policy convener for the New South Wales Branch of the Democrats. He was subsequently selected in the first position on the Democrats' Senate ticket at the 1998 election.
Ridgeway has served on a number of parliamentary and senate committees. In March 2001, he addressed the United Nations Special Session on Racism. He also attended the World Conference Against Racism in South Africa in the same year.
In April 2001, Ridgeway was elected deputy leader of the Democrats, after Natasha Stott Despoja toppled Meg Lees in a leadership spill.
Ridgeway continued as deputy leader until August 2002, when along with fellow senators John Cherry, Lyn Allison and Andrew Murray, he succeeded in forcing Stott Despoja to resign. It was widely tipped that he would succeed her as leader. However, the media did not portray the spill kindly, labelling them the 'Gang of Four'.
Ridgeway was expected to be appointed interim leader however, in a surprise decision, the party's National Executive installed Brian Greig as interim leader due to the role Ridgeway played in forcing the resignation of Stott Despoja. Ridgeway did not contest the subsequent leadership ballot, at which Andrew Bartlett defeated Brian Greig. Ridgeway was technically leader between Natasha Stott Despoja's resignation and the appointment of Brian Greig as interim leader.
Ridgeway also stood down as deputy leader and was replaced by Lyn Allison. Ridgeway did not contest the leadership and stood down as deputy leader as he felt the National Executive's decision not to appoint him as interim leader was a reflection on him in a leadership position.
He remained in the Senate, being particularly active on issues of indigenous affairs and reconciliation. He lost his seat in the 2004 election, along with Cherry, Lees (who had since left the party), and Greig. His term expired on 30 June 2005.
In February 2013, Ridgeway was announced as a spokesperson for the Recognise campaign a movement to recognise Aboriginal and Torres Strait Islander peoples in the Australian Constitution. In May 2013, Ridgeway was one of a number of Aboriginal leaders to start the Journey to Recognition a relay across Australia to raise awareness of the issue. Ridgeway was one of the leading walking participants in the journey.
In May 2006, Ridgeway was selected as the new host of ABC Television's Message Stick program. He is also the inaugural chairman of Indigenous Tourism Australia.
Aden Ridgeway is also an Ambassador of the Australian Indigenous Education Foundation.
Aden Ridgeway was Chairman of Bangarra Dance Theatre from 1998-2010.