Karthik was one of the five stand-byes and has been rewarded for his stupendous form in the domestic cricket last season.
Karthik, who will soon be celebrating his 32nd birthday, scored 607 runs during Tamil Nadu's victorious Vijay Hazare Trophy campaign, including a century in the final. His average was 86 plus and scored the runs at a strike rate of over 100.
He has also scored 704 runs in the Ranji Trophy and another 361 runs in IPL-10, capping off a consistent domestic season.
Having played 23 Tests and 71 ODIs for India, Karthik pipped another glovesman Rishabh Pant, who was also a part of the reserves.
Incidentally, Karthik was a part of the Indian team which won the Champions Trophy, back in 2013.
Pandey had suffered a side strain during one of Kolkata Knight Riders' training sessions and was replaced by Ishank Jaggi during their Eliminator against Sunrisers Hyderabad.