The new site will go live today and the revamp will make it easier for people to search for charities and fundraisers to support, the charity said.
Jonathan Ballin, chief financial officer of Help for Heroes, said that it was a "fairly major overhaul".
"We had a lot of feedback that searching for charities and individuals on the site wasn’t as easy as it should be," he said. "We’re up against sites like JustGiving and we wanted to stay with their pace.
"We haven’t copied JustGiving, but a lot of feedback has been that it has been easier to use than ours has."
Ballin said the redesign had been done by the charity’s in-house IT support staff member and that no external agencies had been used. The project had taken five months to complete, he added.
Bmycharity does not charge commission on any donations made through it, but charges charities a one-off £150 fee to join. A spokeswoman for Help for Heroes said 300 charities and fundraising organisations were signed up to the site.