Ancelotti, however, will remain cautious with Courtois, who has not played since tearing ligaments 13 months ago, with Andriy Lunin set to start Wednesday's Champions League semi-final second leg against Bayern Munich.
"The decisive game we have in mind, a final, is Wednesday's match against Bayern, where Lunin will play. After that, we'll see what happens..." Ancelotti told a press conference.
"(Courtois) is fine, he will play tomorrow after a long, long time. It's good news that he's coming back, just like (Eder) Militao. Courtois can contribute, he's feeling good, he's very excited. We are delighted to have him back."
Ukrainian Lunin has established himself as first-choice goalkeeper ahead of Kepa Arrizabalaga.
Lunin was Real's hero as they beat Manchester City to reach the Champions League semi-finals, making two saves in their 4-3 penalty shootout victory after an inspired performance in the 1-1 second-leg draw.
Courtois, however, is widely considered to be one of the world's best keepers and the Belgian is likely to regain his starting spot with a LaLiga-Champions League double up for grabs.
He was named player-of-the-match in the 2022 Champions League final after making nine saves to deny Liverpool as Real clinched a record-extending 14th European title with a 1-0 win in Paris.
Brazil centre-back Militao returned in late March from an ACL tear suffered in August and made his first start in last week's win at Real Sociedad.
"We were too passive against Bayern. We have to be more active. So Militao will play tomorrow to get into a rhythm," Ancelotti said.
"We are only thinking about the 'final' on Wednesday. We don't think about what might happen in a month's time. We will see... Hopefully, soon we can start looking further ahead, it will mean we'll make the final in London."
With five games left, Ancelotti's side top the LaLiga standings on 84 points, 11 ahead of Barca and 13 clear of third-placed Girona. They can clinch a record-extending 36th Spanish title if they beat Cadiz and Barcelona fail to win at Girona later on Saturday.
