Julian Cadman was among 14 people killed in twin assaults in Spain, according to Catalonia's civil protection agency, which also confirmed the deaths of an Italian and a Belgian persons on Twitter today.
In a heart-wrenching statement, Julian's family described him as "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.
"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," they said, thanking those who helped in the search for the boy.
Julian's grandfather Tony Cadman had posted a Facebook appeal seeking him after a van on Thursday ploughed into crowds on Barcelona's Las Ramblas boulevard which was packed with tourists.
The boy was on holiday in Barcelona for a family wedding but had been separated from his mother, who was found in a hospital in a serious but stable condition.