Real Madrid's Courtois to return after nine-month injury layoff
Belgian international Courtois, 31, has missed the entire season with a knee ligament injury and suffered a further setback in March which required another knee operation.
"Yes, Thibaut is fine. He will play tomorrow (Saturday) after a long period of absence," said Ancelotti.
"He's looking forward to playing. We're delighted to see him return."
La Liga leaders Real Madrid have their first chance to be crowned champions this weekend, although they need a helping hand from this season's shock title challengers Girona.
Madrid host Cadiz on Saturday and if they win and Girona take any points off defending champions Barcelona immediately afterwards, Los Blancos will earn a record-extending 36th Spanish title.
Courtois has been back in team training for several weeks, and was part of the Madrid group to travel to Germany this week to face Bayern Munich in the Champions League semi-final first leg 2-2 draw.
Asked about a possible start for Courtois in the Champions League final if they reach it, Ancelotti replied: "The final we have in mind is Wednesday against Bayern, in which (Andriy) Lunin will play, and then we will see."
In 2022, Courtois was the prime architect of Real's Champions League triumph, proving himself to be one of the best goalkeepers in the world.