The former Manchester United midfielder will replace Marco Verratti for the Coupe de France clash, though Les Parisiens' trainer suggested he may be utilized in a holding role.
The former England captain made his debut for Les Parisiens as a substitute in the 2-0 win over the same opposition on Saturday, and Ancelotti now feels he is ready to start the Coupe de France encounter.
The Italian trainer revealed that Beckham will replace the suspended Marco Verratti in central midfield and could be called upon to play a holding role in the middle of the pitch.
"He will hold the same position as Verratti. He has a full match in the legs. He has the qualities to play midfield and defense as well," he told reporters. "I understand that Beckham is a very important person for the media, but he is a humble boy. This is a player who works hard in training."
Victory in Wednesday's encounter would see Ancelotti's team into the quarterfinals, and though the team is still competing in Ligue 1 and the Champions League, he stressed the importance of progression in the competition.
"This is an important objective. We are now in last 16 and I know that in France, it is a competition that counts," he said. "We should [be] thorough in our performance. We are still playing Marseille and it will still be difficult."
The former Chelsea coach also responded to criticism of Zlatan Ibrahimovic's recent performances, and defended the striker's displays over the past few weeks.
"The fans have forgotten that he has scored 22 goals since the start of the season in Ligue 1," he said of his star. "Even if it was not a good match against Marseille, he scored another goal and he cannot be always 100 percent."