The Jesse Window conservation was completed in November following a three-year, Â£500,000 project.
Free guided tours are being offered for the first time on Saturday and Sunday as part of a weekend of celebrations.
The window is described as one the most remarkable examples of 14th Century stained glass in Europe
It depicts the genealogy of Jesus dating back to Abraham.
Lindsay Mann, from the cathedral, said: "It's the first time visitors are being invited to come in and have tours given by our specialist guides.
"It will focus on the story of the window and also its conservation. The window can now be seen as our mediaeval counterparts intended it to be seen.
"It escaped the reformation, in part due to the sheer scale of it and and its height in the cathedral."
Ms Mann said the free tours needed to be pre-booked via the cathedral's website.
A one-day conference looking at the significance of the window and the process of its conservation will also take place on Saturday.
A recently restored medieval stained glass window at Wells Cathedral is to be shown off during an event to celebrate the project's completion.