Karnataka were reduced to 120 for seven before the lower order came to their rescue.
Number 10 K Gowtham remained unbeaten on 60 captain while the others who chipped in were skipper R Vinay Kumar (39), Robin Uthappa (46) and Sreenath Aravind (26).
For Vidarbha, Lalit was the stand out bowler while Ravikumar Thakur played the supporting role well by taking three wickets.
Karnataka were on put on the backfoot right at start as they lost both openers Ravikumar Samarth and Mayank Agarwal cheaply.
However, Yadav broke Karnataka's backbone with timely strikes. In the end, they did well to cross the 250-run mark.
Vidarbha were 10 for no loss at stumps, having played three overs.