The 25-year-old, who faced 44 deliveries against the Proteas, hit five fours and two maximums to help India pass their victory target of 173 with five balls and six wickets remaining.
"If you look at the importance of this match, then certainly this is my best knock, but I personally feel that I have batted better than this innings on many occasions," Kohli told reporters.
"There has been several T20 innings where I have middled the ball much better than what I did today. There had been instances where I have hit three to four boundaries at the start and my timing was far better. But today, considering the context, this innings will certainly be on top of the list."
India will face Sri Lanka in the final in Dhaka on Sunday.