The auctioneer, which has operated from the site in Diss for most of the last century, hopes to build a new space to host exhibitions and events.
Founded in 1857, the firm said buying the land gave it the comfort to invest in redeveloping the site which is close to the centre of Diss on Roydon Road. It submitted a planning application earlier this year and hopes to start building next year.
The development will include the conversion of some historic livestock pens and the extension of buildings to create a new auction room, restaurant and gallery space, offices and staff facilities.
Director Elizabeth Talbot said: “The new space will lift the profile of our sales as we expand into a more modern space. We will be able to host community events, gallery exhibitions and events such as talks and lectures.”
She added: “We are a significant employer in the town and attract many hundreds of people to Diss each week.”
It currently holds a regular weekly Friday auction as well as some Thursday and Saturday sales with around 3000 lots a week.
TW Gaze, which employs around 75 people, operates estate agency, property surveys and valuations but its art and antique auctions department accounts for around two-thirds of its business.