The Light Blues could only manage a 0-0 draw at third-placed Montrose in a lunch-time encounter but that point ended up clinching them the title when Queen's Park slipped up in the afternoon.
The second-placed side lost 1-0 at home to Elgin, a 57th minute penalty from Stuart Leslie giving the visitors the three points and ensuring that Rangers claimed the title with seven matches to spare.
Ally McCoist's side were demoted from the top flight to the bottom tier of Scottish football after they were liquidated in the summer.
They have not been wholly convincing of late, suffering a shock home defeat to Annan Athletic and stumbling over the line with a pair of goalless draws.
But they were a long way clear of the chasing pack by then and will lift the trophy when they play host to Berwick Rangers on 4 May.
However, with talks still ongoing about the future set-up of the game in Scotland, it is unclear what division the Ibrox club will start life in next season.