|Julian Cadman was among the victims in Barcelona|
The seven-year-old, who had dual UK-Australian nationality, died after a van was deliberately crashed into pedestrians on Las Ramblas on Thursday.
He was separated from his mother, who was badly injured and she is said to be in a serious condition in hospital.
His relatives said: "Julian was a much loved and adored member of our family. As he was enjoying the sights of Barcelona with his mother, Julian was sadly taken from us.
Julian's family has paid tribute to the boy
"He was so energetic, funny and cheeky, always bringing a smile to our faces. We are so blessed to have had him in our lives and will remember his smiles and hold his memory dear to our hearts.
"We would like to thank all those who helped us in searching for Julian. Your kindness was incredible during a difficult time.
"We also acknowledge we are not the only family to be affected by the events, our prayers and thoughts are with all people affected."
Julian's relatives said he was 'funny and cheeky'
The Spanish missing persons bureau had earlier confirmed his death.
|Julian's relatives said he was 'funny and cheeky'|
"In these very unjust, hard and painful moments, we accompany Julian's family and friends. Rest in peace."
The statement released by the Spanish missing persons bureau about Julian
A Foreign Office spokesman said: "We are assisting the family of an Australian-British child who was killed in the Barcelona terrorist attack.
"His family have our deepest sympathies at this very difficult time. Our staff are doing all they can to support them, working with our Australian colleagues and the Spanish authorities."
:: Who are the victims of Spain terror attack?
Following Thursday's atrocity, it had been unclear what had happened to British-born Julian, who lived in Sydney.
His father and grandmother travelled to Spain from Australia following the attack.
And his grandfather Tony Cadman had urged people to share a photograph of Julian on Facebook as fears grew for his safety.
A Belgian and an Italian have also been confirmed as being among the dead in Barcelona. At least 120 other people were injured.
Police said the van driver was part of a Islamist extremist cell which also attacked members of the public in the coastal resort of Cambrils a few hours after the Las Ramblas atrocity.
A woman was killed in the second vehicle rampage, and several other civilians were injured, along with a police officer.
Some 34 nationalities were among those hurt in Las Ramblas and Cambrils, which lies around 70 miles to the south west.
Meanwhile, Spain's King and Queen have
attended a mass at Barcelona's Sagrada Familia basilica for the victims.
Also, police have identified two bodies
found in a house destroyed by a huge blast linked to the attacks.