The Brazilian winger suffered a hamstring injury in November which was expected to keep him out until the Intercontinental Cup final on December 18.
However Vinicius was able to train on Friday and Ancelotti said he would return next week, missing Saturday's La Liga visit to face Girona.
"Vini has recovered from his injury very well, he will not be ready for tomorrow but he will be for the next Champions League game," Ancelotti told a news conference Friday.
Vinicius' return bolsters a Madrid side which has suffered three defeats in their opening five European matches, sitting 24th in the Champions League group table.
The coach said defender David Alaba, who also trained with the team, was finding fitness after a long-term knee injury and could return in January.
With Vinicius sidelined, even more focus has been cast on misfiring superstar striker Kylian Mbappe after his arrival from Paris Saint-Germain in the summer.
The French forward missed penalties in defeats by Liverpool and Athletic Bilbao in the past fortnight and is struggling to find his best form, with 10 goals in his first 20 matches across all competitions.
Mbappe posted on social media network Instagram to say he would "change this situation" and show his true colours.
"He is conscious (of it), the post he put out after the game is that of a player who knows what he is doing and also what he can do, and will do," said Ancelotti.
"Obviously we're with him, he's not at his best level, but there are many players who are not at their best levels and don't know it -- he does know it."
Ancelotti said he was encouraged by Mbappe's performances in recent La Liga matches against Getafe and Athletic.
"In the last couple of games in terms of intensity he improved a lot," said the coach, citing Mbappe's sprinting statistics.
However Ancelotti accepted resting the 25-year-old might also help him at some point.
"We have to support him, but supporting him does not mean he has to play all the games. Sometimes it could be that a day of rest could be good for him."
The coach felt he himself was also being attacked too much over Madrid's recent form, although admitted he had "to accept" some criticism.
"Like stress, criticism is fuel to try and do better," added Ancelotti.
