Orissa, after winning the toss, asked their southern rivals to bat first and then applied the skids when Karnataka seemed in sight of a score in excess of 300 to restrict the latter to 284 for nine in 50 overs.
Orissa raced towards the target with an opening stand of 83 in only 51 balls between C Mahapatra, who cracked 50 in only 26 balls with the help of 4 sixes and 5 fours, and Shiv Shunder Das (82 retired off 66 balls).
After the departure of Mahapatra, Das - who hit 14 fours - and one-down Rashmi Ranjan Parida, who made 53 off 77 balls, carried the score to 172 when the former was forced to retire because of a bout of cramps.
Karnataka seized the opportunity to strike three quick blows and reduce Orissa to 211 for four in the 34th over when M Behera and P Jayachandra got together to stitch an unbroken stand of 74 runs and carry them past the finish line.
Behera remained unconquered on 33 in 38 balls while Jayachandra, who struck leg break bowler Barrington Rowland for two successive sixes over the straight field, was not out with a run-a-ball 35 that included two fours too.
Earlier, Barrington Rowland scored a fine 104 in 123 balls with 8 fours and put on 153 runs in 150 balls for the second wicket with Sujit Somasunder, who smashed 77 in as many balls with 7 fours and 2 sixes, before the innings lost its momentum.