Ansu, 18, has not played since injuring the meniscus in his left knee in a 5-2 win over Real Betis last November. Several operations have been required to fix the problem, but the Spain international returned to full training earlier in September and he has been included in the squad for Sunday's LaLiga game against Levante.
Coach Ronald Koeman said that Ansu, who recently inherited the No.10 shirt from Lionel Messi, is only ready for a "maximum of 15 minutes" and warned that it could take a while for him to return to top form.
"It's very important to have him back, firstly for the player himself, because he has been out for a really long time," Koeman said in a news conference on Saturday. "We have a plan with him and we will continue to follow that plan to ensure he returns properly.
"It's going to take time for him to get back to where he was before the injury. We won't look to run with him before we can walk. It will depend on his response and briefings with the medical team. We're talking about a young player who will add a lot of quality to the team, but we have to take it step-by-step."
Ansu was Barca's top scorer last season at the time he picked up the injury, with five goals from 10 games.. In the previous campaign, he had become the club's youngest ever scorer in LaLiga and the youngest in the Champions League for any team.
In total, he has made 41 appearances for the first team, scoring 13 goals.
His return coincides with Barca struggling to score goals. They are winless in three games and have scored just once in that time, in Monday's 1-1 draw with Granada, which was followed by a goalless draw against Cadiz on Thursday.
As well as Ansu, Koeman has also been without forwards Ousmane Dembele, Martin Braithwaite and Sergio Aguero in attack this season due to injuries, while Messi, Antoine Griezmann and Francisco Trincao all left the club over the summer.
"We are limited in attack," the Dutch coach added. "We have [had some] big losses because we're talking about players that can play wide, that can run at defenders and that have pace. That always makes it more difficult to defend against us.
"We try to look for our way of playing, but if we lack wingers to play on the wing, it's difficult. We have full-backs that play as wingers, but they're not. And [the players playing wide right now] are players that want to play inside.
"Since the start of the season, we have done a lot of things. As coach, I have accepted the departures of players for the economic good of the club."
Recent results have increased the pressure on Koeman, who will serve a touchline ban on Sunday after getting sent off against Cadiz, with sources telling ESPN the club are already exploring possible replacements.
"For a while now I have not been reading the press very much," Koeman added when asked about his future. "I know the rumours. The only thing I can do is focus on winning games."
Barca, who have nine points from their first five league games, will be without Jordi Alba, Pedri, Dembele, Aguero and Braithwaite against Levante this weekend, while Frenkie de Jong is serving a one-match ban.