The 10-year fix at a rate of 2.69% is available to house buyers or remortgage customers at 75% loan to value (LTV) and comes with a £995 product fee and free standard valuation.
Borrowers can make annual overpayments by up to 10% without charge, and the mortgage is portable.
Accord said the deal comes amid rising demand for longer term fixes, sparked by expectations the Bank of England will soon hike core interest rates.
Jemma Anderson, mortgage manager at Accord, said: “We felt it was important to offer a mortgage which will give borrowers long-term value for money and provide them with the reassurance of knowing exactly what their monthly repayments will be for a decade come what may.
“The current rate conditions allow us to offer a highly competitive rate on our 10-year fix, which is significantly below the 3.05% market average rate.
“Life is constantly changing, so the new mortgage is portable which gives borrowers the flexibility to take their deal with them if they decide to move home before it comes to an end.
“Locking into a deal for this length of time is a big decision, so brokers can add value for their clients by helping to make sure they are aware of all their options before signing on the dotted line.”