Kohli, who missed the second Test because of an upper back spasm, had nets with the rest of the team at Newlands on Sunday. He batted without any visible discomfort, lunging forward to play the drives.
“I am absolutely fit,” Kohli said at the pre-match press conference.
However, he added that Siraj will not feature in the game after he suffered a hamstring injury in Johannesburg, where India lost by seven wickets.
Team India will look to bounce back in the third and final Test of the series, which is scheduled to begin Tuesday.
India kicked off the South Africa tour on a perfect note, crushing the hosts by 113 runs in the series-opener at Centurion.
However, the Proteas won the second game to leave the three-match series level at 1-1.