All branch staff and dealers within the business and equipment finance units will now be using Sovereign, an application provided by New Zealand-based Finzsoft.
Later this year the automobile financing system will be converted to run the Sovereign application.
According to a St George spokesperson, the bank is moving away from a mainframe environment, because it is "past its use-by date".
The spokesperson could not confirm what the bank was moving towards using as a backbone upon implementation of Sovereign.
St George Bank CIO, John Loebenstein, said the rollout of Sovereign is a major project, and Finzsoft was chosen after a review of other suppliers in the market.
Barrie Shannon, Finzsoft Solutions managing director said St George is currently upgrading all of its delivery systems.
He confirmed the Finzsoft deal is worth "millions of dollars", but did not provide specifics.
"The business equipment lending application is live across Australia now and the automotive application goes live in the second half of this year. It is a two-year project," Shannon said.