More than 4,000 people had joined a Facebook group set up by the NUS with the name "Stop the Great HSBC Graduate Rip-off!!!" after HSBC decided to charge interest on a £1,500 overdraft facility that had previously been offered for free.
People appeared to continue to join the group after the NUS announced its success, with membership crossing the 5,000-mark this afternoon.
Initially the bank had argued that this would help students get the message that there is a cost to borrowing, and help them make the transition from student life to working life.
However, HSBC has since backtracked under the weight of the bad publicity.
Andy Ripley, head of product development at HSBC, said: "Like any service-oriented business we are not too big to listen to the needs of our customers.
"Following the feedback from our graduate account holders, both directly and via the NUS, we have taken the decision to freeze interest charging on 2007 graduates' overdrafts up to £1,500 and refund any interest charged in August."
The union hailed the role of Facebook in securing the backdown, the NUS said that there was "no doubt" that the group had made the world of difference.
It is not the first time consumers have put pressure on corporations via Facebook. A recent push to get Cadbury to bring back the Wispa chocolate bar succeeded, partly inspired by a number of groups on Facebook, as well as MySpace and Bebo.