The shop, which celebrated its seventieth birthday on Monday 26 October, raised more than £3,000 to expand into the cellar and provide a wider selection of books for customers.
Co-manager Catherine Barter said: “Its really gratifying that lots of people are really excited about the shop. We’ve started the development already, and hopefully it will be open by the end of November. We want to get up and running as soon as possible.”
The online campaign, which met its target in just over three weeks, came while many other independent bookshops were shutting down.
“We have a lot to celebrate,” Ms Barter added. “The shop has lasted through some difficult times for independent bookshops. This is because what the shop does is unique. We have stayed true to our radical image and this has worked for us.”
Housmans has hosted talks by leading left-wing figures including Labour Party leader Jeremy Corbyn and Canadian activist Naomi Klein.
“This is a politically interesting time,” Ms Barter said. “And a space like this becomes important now more than ever. It is a good hub for activity. New people are discovering us all the time”