The contract comes two weeks after Dembele's previous deal with Barcelona expired, and ends months of speculation when at times he looked to be more likely to leave than to remain at the club
Dembele went down in the penalty box and had to be replaced at the 26-minute mark by countryman Antoine Griezmann.
The club has identified one target each from La Liga, Ligue 1, and Bundesliga to try and draft in star players in the team and strengthen their weak-looking side.
Ousmane Dembele was the latest to join the injured list with a left hamstring strain that will keep him on the sidelines for five weeks.
FC Barcelona on Monday announced that its France forward Ousmane Dembele has been diagnosed with a sprained left ankle that would sideline him for about 15 days.
Barcelona overturned a first leg defeat to beat Levante in the Copa del Rey but could yet be thrown out of the competition after being accused of fielding an ineligible player.
Barcelona held off Atletico Madrid to ensure they will be three points clear at the top of La liga going into the winter break after beating a spirited Espanyol 2-0 at the Camp Nou on Saturday.
Buzz surrounding the former Borussia Dortmund player re-emerged at a press conference ahead of Barça's upcoming UEFA Champions League match against Tottenham Hotspur after Dembele arrived two hours late for training on Sunday, reports Efe.
Puyol also seemed to acknowledge Dembele getting left out during Barcelona's 4-3 loss to Real Betis on Sunday.
Coutinho will not play against Betis. The midfielder is recovering from a hamstring strain.
