Riquelme was born as the eldest of 11 children in a poor family, one day before Argentina won the 1978 World Cup. He began playing footballing in the localities of San Fernando, playing for different local clubs, before gaining the opportunity to trial with the junior teams of Argentinos Juniors. After trialling, he was signed by the club where he began playing as a central mid-fielder. Boca Juniors and River Plate spotted him when he was a youth player for Argentinos Juniors. In 1995, however, Riquelme was transferred from Argentinos Juniors U-20 to Boca Juniors U-20 for a fee of US$800,000, during an operation insisted by trainer Carlos Salvador Bilardo which led to the then president of Boca Juniors, Mauricio Macri, establishing various purchases of Argentinos Juniors youth players.On 10 November 1996, aged 18, Riquelme made his Primera División debut in a 2–0 win against Unión de Santa Fe. Two weeks later, he scored his first senior goal in a 6–0 triumph over Huracán.