Dr Singh was accused by the Opposition of occupying office of profit by being the president of Indian Council for Cultural Relations.
He has sent his letter of resignation to party president Sonia Gandhi.
Dr Singh's resignation came hours after Mrs Gandhi announced her resignation as a Lok Sabha member and Chairperson of the National Advisory Council (NAC) following complaints seeking her disqualification for holding an office of profit.
In a statement issued here, Dr Singh said,'' I am conviced that neither the presidentship of the Indian Council for Cultural Relations nor the Chairmanship of the Auroville Foundation constitutes offices of profit. I, however, feel that as my name has also figured in the media, and as in my public life of over half a century I have always striven to uphold the highest principles of polity and propriety, I should resign from the Rajya Sabha.'' ''To quote Soniaji, I feel that this is the right thing to do. I am, therefore, sending my letter of resignation to my party president Sonia Gandhi.'' Dr Singh is also the Chairman of Rajya Sabha's Ethics Committee, which had recommended the expulsion of two members of the upper House for ''misuse'' of MPLAD scheme.