The creative Argentine midfielder, a notable absentee from Diego Maradona's 2010 World Cup side, will be 36 when the contract concludes in 2014, the year Brazil host the next World Cup.
The deal was a long time on the table and the final decision to accept Riquelme's terms earlier this week split the club's board of directors down the middle, with president Jorge Amor Ameal's vote tipping the balance 9-8 in favour.
"We've finished the way we all wanted...The most important thing is that I'm going to be at the club a lot longer to defend the colours I love so much," Riquelme told reporters at the signing.
He is recovering from knee surgery in May and wants to get fully fit before playing again, possibly coming back in the team's seventh or eighth match of the Apertura championship that started last weekend with Boca being held 1-1 away to Godoy Cruz.
Due to personal differences he was overlooked by Maradona for this year's finals, which ended at the same stage for Argentina in a 4-0 rout by the same opponents.
