The deal is charged at a variable rate of 3.99% in the first year, rising to 4.89% in years two and three.
These rates are variable and could be subject to rise if Cambridge increases its Standard Variable Rate, a move most likely to happen if the Bank of England were to hike its Base Rate.
In the first year this mortgage is markedly cheaper than the deals currently available under the second phase of the Help to Buy scheme.
Cambridge Building Society said this would give first-time buyers lower monthly payments and help them to meet the set up and decorating costs of establishing a home.
Last month, RBS-NatWest and Lloyds Banking Group unveiled their Help to Buy products, available up to 95%.
RBS-NatWest offers a two-year fixed-rate deal at 4.99% with no fees, while Lloyds brands Halifax and Bank of Scotland offer 5.19% on their two-year fixes, with a £995 fee.
Clydesdale and Yorkshire banks responded by cutting the rates charged on their regular (non-Help to Buy) three-year fixed-rate mortgages from 5.49% to 4.99%, for borrowers with a 5% deposit.
It is hoped that the number and cost of mortgage deals available up to 95% LTV will improve in the new year, when more lenders launch their Help to Buy 2-backed deals.