Rajasthan bowlers, led by spinner Pravin Tambe (4/20), justified their skipper's decision to bowl first as only three batsmen could touch a double-digit mark.
RCB's total was third lowest in tournament's history.
Ironically in 2009, Rajasthan were at the receiving end of Bangalore's hostility when they were bundled out for 58 - the lowest IPL score by any team till now.
The RCB innings was off to a disastrous start after their openers returned to the dug out in the very first over and the agony ended for them in the 15th over.
Medium-pacer Stuart Binny got Yogesh Takawale caught behind for nought and the in-form Parthiv Patel followed him soon after being run out for 1.
Australian pacer Kane Richardson then replaced Binny in the third over to choke the RCB top-order after picking up the prized wickets of Yuvraj Singh (3) and AB de Villiers (0) on consecutive deliveries. The hat-trick ball was foiled by Sachin Rana.
Rana, who plays for Haryana in Ranji trophy, though couldn't last long after he was cleaned up by Watson for 3.
The rot continued after leg-spinner Tambe got Albie Morkel for 7. Albie, who had been patient till now, went after a flighted delivery to lob a simple catch to Steven Smith at mid-off.
Skipper Virat Kohli (21) tried his best to resist the fall but the attacking batsman gave away a sitter to Tim Southee at mid-off off Tambe.
On any other day it would have been four but Kohli seemed to have been bitten by the same bug that hit the rest of his mates.
The procession continued as Mitchel Starc was caught by Binny off Rajat Bhatia after a fighting 18. Tambe then completed the formalities to wipe off the tail.