Newly-promoted Rovers looked set to continue their dream start to life in the Championship when Lewis Guy struck for the second successive Saturday in the 67th minute.
But Scotland striker Ross McCormack, who had a spell on-loan with Doncaster three seasons ago, snatched a fortuitous late equaliser.
Doncaster began brightly and had all the pressure playing some splendid football in the first 20 minutes.
Richie Wellens had a shot deflected wide following a free-kick from Brian Stock in the sixth minute and James Hayter hit a 20-yarder just wide a minute later.
A goalbound effort from Stock rebounded off team-mate Gareth Taylor in the 12th minute as Cardiff continued to weather the storm.
But the visitors held firm in defence and began to assert themselves in the latter stages of the first half with home keeper Neil Sullivan doing well to tip away a penetrating cross from Kevin McNaughton in the 23rd minute.
Sullivan produced a super-reflex save to deny Paul Parry a minute later, before Doncaster got on top again with Taylor hitting a powerful low shot which Tom Heaton did well to save.
Doncaster had more of the play in the second half, although Cardiff coped comfortably until Guy struck what seemed likely to be the winner.
The former Newcastle striker latched onto a long ball down the middle from Matt Mills and lashed home an unstoppable shot into the bottom corner.
Cardiff's attempts to hit back looked feeble and they seldom posed a threat until they were gifted an 88th minute equaliser following a collision between keeper Sullivan and skipper Adam Lockwood.
The ball ran to the waiting McCormack, who gleefully fired home from close range to give the Welshmen a point they scarcely deserved.