Barcelona's players will bear the city's name on the back of their shirts in tribute to the victims of Thursday's deadly attack in the Catalan capital when they play Real Betis in La Liga on Sunday, the club said in a statement.
Barca have been granted special permission from the Spanish soccer federation (RFEF) for the arrangement, and said the message "#TOTSSOMBARCELONA" ("We are all Barcelona") will be embroidered on the front of the soccer team's shirts.
The club added that the players will also wear black armbands during Barcelona's opening league game of the season.
At least 13 people were killed and more than 100 were injured when a van ploughed into crowds of people on the renowned Las Ramblas boulevard.
A woman died after an attack later on Thursday in the coastal town of Cambrils, south of Barcelona, where police shot dead five suspects who drove their car at pedestrians.
Barca said on Friday that their shirt tribute is for the victims of the attacks in Barcelona and Cambrils.
Ernesto Valverde's side and Betis will join the other 40 teams in Spain's top two divisions in holding a minute's silence before every game at the weekend.