The deal with Bank of Scotland, Barclays Corporate and Santander UK is for a £37.5m term loan and a £32.5m revolving credit and overdraft facility.
Both run until December 2014, with options to extend until March 2016 if STV's broadcast licences are confirmed by the end of 2013.
The term loan will decrease by £7.5m by the end of this year, then by a further £5m at the close of 2013 in line with STV's expectations to decrease its net debt.
Analysts said the broadcaster, headed by chief executive Rob Woodward, had agreed to the lending at four percentage points above the inter-bank lending rate (Libor), which is effectively double the previous deal it had.
The greater cost of the financing is due to increases in Libor, which has grown to its highest level since July 2009 amid worries over the eurozone.
George Watt, chief financial officer at STV, said: "It is fair to say that our margins over the Libor rate are almost double what we were paying but that is in line with what is happening in the market.
"It is more important to have the certainty of the funding and the margin is part and parcel of where the market conditions are.
"The amortisation of the facility reflects the cash generation of the business, and that net debt is forecast to fall by similar levels across the period.
"It is something both we and our banking partners wanted.
"We don't need that level of facility given how much we expect net debt to fall and the banks are always keen to have some amortisation.
"These new facilities will provide the group with certainty in the medium to long term and flexibility to continue to pursue our growth ambitions."
The new agreement replaces the facility that was fully funded by Bank of Scotland and was due to expire in December this year.
Analysts are forecasting net debt at STV will be around £55m for the 2011 year end, before dropping to £45m to £50m in 2012 and hitting £40m by 2013.
Peel Hunt and Investec Securities suggested the extra interest charge would trim STV's earnings by 3% this year and 2% next. A note from Patrick Yau at Peel Hunt said: "Clearly it is a difficult environment in which to renegotiate commercial banking arrangements, but we believe that the new facility brings certainty over the financing of the business, albeit at an unavoidable cost.
"STV will work hard to mitigate this but cannot completely offset the impact."
Mr Watt said STV's pension scheme deficit may widen but that had no impact on the negotiations with lenders.
He added: "We don't have the numbers yet for the year end but the expectation would be that the deficit will have widened given what has happened in the market, particularly with gilt yields coming down."
The deficit had reduced from £16.2m at the end of 2010 to £8.9m in interim results for the six months to June 30, 2011.
STV's shares ended the day up 3.75p at 102p.