Platini, 60, and former Fifa counterpart Sepp Blatter were last year found guilty of ethics breaches over a $2m (£1.3m) "disloyal payment".
Platini spent eight hours on Friday with the three-member CAS panel.
"I explained the truth, I have nothing to reproach myself for," Platini said.
Both Platini and Blatter, who deny wrongdoing, had their original bans upheld by the Fifa appeal committee, but reduced from eight to six years after the committee considered the duo's "activities and services rendered to Fifa, Uefa and football".
Platini wants the Lausanne-based appeal committee, led by Luigi Fumagelli of Italy, to annul the verdict.
Fumagelli was a member of the panel which upheld a four-month ban for Barcelona forward Luis Suarez for biting an Italy defender when playing for Uruguay at the 2014 World Cup.
Fifa's ethics and appeal committees ruled there was "not sufficient evidence" to establish the payment was a bribe but said both men demonstrated an "abusive execution" of their positions.
Blatter, 80, is likely to attend the hearing to give evidence about the Fifa payment he approved for Platini in 2011 as backdated, uncontracted salary.
Blatter's appeal against his six-year ban will be heard at a later date.
Gianni Infantino has succeeded Blatter as Fifa president, while Uefa has named Angel Maria Villar as acting president.