Westpac says about 14 percent of its applications for home loans are now being lodged online.
The bank said its mortgage book grew by $2.2 billion to $38.6 billion at the end of March from a year earlier.
More than half its customers were now actively using online banking and 39 percent were using mobile banking services.
Chief executive Peter Clare said online and mobile applications were a rich source of new customers for Westpac.
"One of the features we have is that once you've completed the input form and press return, you get an answer back within 60 seconds with an unconditional yes or no, obviously subject to improving your income and employment and where you live and so forth.
"But you can actually rely on that to then go and make a real bid at an auction or a private treaty sale."
A majority of the applications were being made between 7pm and 9.30pm on weeknights and about half of the applications through the mobile application channel were new to Westpac.