The 2008 FIFA world player of the year and favourite for the 2013 award has missed three matches with a hamstring injury suffered at Almeira.
Xabi Alonso, Ronaldo and Gareth Bale all missed Real's goalless draw away to lowly Xatvia in the Copa del Rey round of 32 at the weekend.
However, all three have been confirmed in Real's 20-man travelling party, with Ronaldo looking to add to his eight goals in four group games, two of them in the 4-0 home win over Copenhagen.
Carlo Ancelotti's men have scored 18 goals in their five matches so far and require three more to overtake the group stage record of 20 from Manchester United (1998/99) and Barcelona (2011/12).
With Real's progress assured, Ancelotti may be inclined to use Ronaldo sparingly, but he could combine the Portuguese with Bale and Karim Benzema in a strikeforce Copenhagen will be fearful of facing.
"Cristiano is fine, he is training with the rest of the team and he will play on Tuesday without any problem," Ancelotti said.
Four players are already out, with Sergio Ramos suspended and Fabio Coentrao, Sami Khedira and Raphael Varane injured, while Nacho will start in defence alongside Pepe, Ancelotti has said. Defeat to Juventus in round five means Copenhagen cannot advance in the Champions League.
However, Stale Solbakken's men can go through to the Europa League if against Real they can better Galatasaray's result against Juve.
The Danes are unbeaten at home in the previous two games.
"We are still alive and we will hope that we can provide one last, brave effort to go through," Solbakken said on www.fck.dk.
"I have said that I hope for one Christmas present before December 24 and that is a win or maybe a draw in Parken (against Real)."
Three of Copenhagen's most creative players appear likely to be out of the match, with Nicolai Jorgensen, Daniel Braaten and Rurik Gislason struggling.
"It looks very difficult for Gislason and Braaten to recover but we still hope that Nicolai Jorgensen will be fit enough to play," Solbakken told bold.dk. "As we are hit by injuries at the moment, I consider everybody. Just tie your boots and join the training. Maybe you will be in the line-up for the game against Real Madrid."