The first "alternative giving" window was installed in Castle Street in April, and another one has now been created in Pride Hill.
The windows contain a specially-designed card machine which people can use to make donations directly to Shrewsbury Ark, rather than giving rough sleepers their loose change.
Mike Matthews, chair of Shrewsbury BID and trustee of the charity, said the windows had been installed as the result of a partnership between the two groups.
“Shrewsbury BID works closely with The Ark, and providing a safer, more targeted way for people to help the homeless is something we have wanted to do for some time,” he said.
“Providing structured support to help homeless people get their lives back on track is much more beneficial than simply giving them some money, which is why these alternative giving windows are so important.
“The alternative giving windows are really easy to use - you just tap your card or device on the machine to make a £3 donation.
“There are also secure cash giving boxes in The Square, Frankwell and the railway station, if people prefer to donate that way - either way, the money goes straight to The Ark.
“The charity provides vital support to help people turn their lives around - everything from basic food and washing facilities to helping them find a job and a more permanent place to live.
“I am really proud that we are working together to deliver such an innovative scheme here in Shrewsbury.”
Wendy Faulkner, manager of The Ark, added: 'The Shrewsbury Ark relies on contributions from the public. Without you, the Ark would simply not exist.
“Through the amazing public's generosity, we can continue to offer a variety of services, activities and support for individuals who can feel excluded from society.
“We are privileged and honoured that people allow us to be a part of their lives and are so proud to stand by their side through their journey. We are a safe place, a safety net, but more than anything we are the Ark Family and each and every person in need will always be welcome.
“The funds from the alternative giving scheme will support our work towards ending homelessness and ensuring that everyone has a safe place to call home.”