Valthaty, 27, clobbered 19 fours and two sixes in a stunning counter-attack to help Punjab overhaul an imposing 189-run target with five balls to spare for their first win in two matches.
A surprise promotion to the opening slot, Valthaty single-handedly fashioned the highest successful run-chase in the ongoing Twenty20 tournament.
Dinesh Karthik brought off the winning runs with a six, much to the delight of Adam Gilchrist's team, reeling under a heavy defeat to Pune in their opening match.
Opener Murali Vijay earlier struck a fine 74 off 43 balls to help Chennai overcome the loss of two wickets off the first two balls of the innings.
Vijay also shared a 122-run partnership for the third wicket with Subramaniam Badrinath who remained not out on 66 with eight fours, after Punjab won the toss and elected to field.
Fast bowler Praveen Kumar gave Punjab the perfect start when he had in-form opening batsman Anirudha Srikkanth trapped leg before and Suresh Raina caught at midwicket the next ball.
But Vijay and Badrinath brought the innings back on the track with a mix of aggression and caution and set the stage for a late assualt by skipper Mahendra Singh Dhoni.
Dhoni smashed four fours and two sixes to score 43 runs off 20 balls as his wife Sakshi cheered from the stands.
Brief scores:
Chennai Super Kings 188-4 in 20 overs (M. Vijay 74, S. Badrinath 66, M.S. Dhoni 43; P. Kumar 2-37) lost to Kings XI Punjab 193-4 in 19.1 overs (P. Valthaty 120 not out) by six wickets.
