Ramnivas Ruia Junior College, which celebrated its Silver Jubilee on the eve of the new millenium (2000-01), had its inception in July 1975, when the State of Maharashtra adopted the 10+2+3 pattern following the recommendations of the Kothari Education Commission (1964-66). It was started as a separate administrative unit in the same premises of its parent institution, Ramnarain Ruia College (estd. 1937), which has the distinctive privilege of being one of the 31 institutions run by the prestigious private educational society in Maharashtra, the Shikshana Prasaraka Mandali (Pune), the seventh college in Mumbai after Elphinstone College (1856), Wilson College (1861), St. Xavier's College (1868), Sydenham College (1913), Institute of Science (1924) and Ismail Yusuf College (1930), and the first private college in the city.

Following the introduction of new courses at the +3 stage (Degree College), expansion of various existing departments and laboratories and consequent phenomenal growth in its student strength, need for more physical space culminated in the erection of a new building, alongside the old building, for the Junior College which was inaugurated on 29th February, 1996. However, in the larger interest of a healthy academic atmosphere, for staff and students alike, the physical separation of the +2 and +3 stages was considered inadvisable. Accordingly, all the curricular and co-curricular activities of the Degree and Junior Colleges are spread over both the buildings.