Sent into bat, the Northeastern state were 92 for the loss of four wickets but the middle order denied Karnataka total upperhand.
Speedster N C Aiyappa dismissed Sajjad Hussain (11) and Kiran Pawar (zero) in successive balls, reducing the visitors to 29 for two. Thereafter, Parag Das, who top-scored with 45 with eight fours, and S Vasant Saravanan (31) steadied the boat.
Wicket-keeper Zakaria Zuffri contributed 43 with seven fours, while R Satish rattled up an enterprising 37 in 29 balls with six fours and one six to lend some respectibility to their side's day-one score.
Aiyappa and spinners Sunil Joshi and Udit B Patel shared two wickets each while Dodda Ganesh took one.
Wet outfield because of overnight rains ensured that only 65 overs could be bowled on Thursday with the match beginning at 12.50 hours (IST).
Facile 10-wicket win for Karnataka