In 1997 he was appointed Attorney General, but resigned as a consequence of heavy criticism related to the 'Bar-On Hebron' scandal, which involved allegations against chief officials that they recommended Bar-On to the position for personal reasons. Bar - On resigned within 48 hours.
Prior to his political career, Bar-On served, among others, as Chairman of the Council for the Organisation of Sport Gambling (1998–2001), member of the Central Committee of the Israel Bar (1995–2003) and the Jerusalem Regional Committee of the Israeli Bar, as well as a member of the Council for the Administrative Courts, the Advisory Commission to the Government Companies Authority and the Public Defenders Commission. In addition, he served as Chairman of Beitar Jerusalem's committee, and also on the committee of the Israel Football Association.
Bar-On entered the political world when he was elected to the Knesset in 2003 on the Likud list. He served as chairman of the House Committee, and a member of the Constitution, Law and Justice and State Control Committees, as well as a substitute member of the Foreign Affairs and Defense Committee. He was also a member of the parliamentary inquiry committee on violence in sports, as well as the Environmental Lobby. He also served as member of the Parliamentary Inquiry Committee for Uncovering Corruption in the Government System of Israel.
In the 2009 elections he retained his seat after winning fifth place on Kadima's list, but lost his place in the cabinet as the Likud-led coalition formed the government. As a leading member of the minority in the Knesset, Bar - On was elected to head the Knesset State Control Committee on July 2011. As a part of a coalition reshuffle, Bar - On was then elected for the position of Head of Foreign Affairs and Defense Committee. On 5 December 2012, in the days leading up to the 2013 elections, Bar-On announced he would not be contesting the elections.