Bartra, who made his debut for Spain in November when he played in the 2-1 win over Ecuatorial Guinea, would have been out of contract at the end of the current campaign. (Agencies)
The club has convinced him to extend his agreement with them until for a further three years until the end of June 2017 and to raise his buyout clause to 25 million euros.
It is a birthday present for the player who celebrates his 23rd birthday on Wednesday and the reward for a season in which he has finally been able to establish himself as a fixture in the Barcelona first team squad.
Bartra has made 11 appearances in the BBVA Primera Liga this campaign, as well as two in the Champions League and one in the Copa del Rey and has shown himself to be a solid, fast and brave defender, who is very comfortable surging into the opponents' half to create scoring chances.
Last season, Bartra looked as if he could struggle to make the final step forward into the Barca first team as he made just eight appearances in the league and played a total of just 16 times in all competitions, despite the injuries suffered by Carles Puyol and Javier Mascherano.
Former coach Tito Vilanova at times even preferred playing full back Adriano Correia in a central role, despite the fact that at 1.72 Adriano was at a considerable height disadvantage defending set pieces. But this season Tata Martino has shown confidence in the youngster, who has previously been a fixture in the Barcelona B-team in the Spanish second division.
With Bartra's future being secured, the club will now turn its attention to renewing full back Martin Montoya, who will also be out of contract at the end of the season and has been linked with several sides in England, and Gerard Pique, whose current contract expires at the end of June 2015.
Barcelona will play away in Getafe in the Copa del Rey on Thursday night, but after winning the first leg of their last 16 tie 4-0, they are in little danger from a side which has taken just four points from their last eight matches in the Primera Liga.
Bartra, who made his debut for Spain in November when he played in the 2-1 win over Ecuatorial Guinea, would have been out of contract at the end of the current campaign.