Doncaster clinched promotion to Division Two only 12 months after coming up from the Conference.
The side who were early relegation favourites sealed their triumph by extending their unbeaten run to 14 games against Cambridge.
Doncaster broke through on the hour when Adebayo Akinfenwa forced Greg Blundell's cross home from close in.
Paul Green's spectacular diving header five minutes later set up the lap of honour and wild celebrations.
Doncaster: Warrington, Price, Foster, Morley, Mulligan, Melligan, Doolan, Ravenhill, McIndoe, Akinfenwa, Blundell. Subs: Rigoglioso, Fortune-West, Green, Brown, Collin.
Cambridge Utd: Marshall, Angus, Tann, Goodhind, Murray, Nicholls, Guttridge, Smith, Tudor, John Turner, Easter. Subs: Ruddy, Chillingworth, Bridges, Bimson, Webb.
Referee: E Evans (Manchester)