The venture at Bronzefield Prison, Surrey, allows offenders to learn about baking cakes and arranging flowers.
Members have also enjoyed talks on bee-keeping, taken part in craft events and even hosted a coffee morning for WI ladies from the affluent commuter village of Virginia Water.
The prison is a top-security institution which houses murderers and high risk offenders, including Rosemary West at one time, as well as lower grade prisoners.
The group of around 40 members, aged between 19 and their late 60s, meets in a room on the prison estate, decorated with handcrafted paper butterflies.
It is open to those on resettlement programmes to prepare them for release as well as staff members and includes a book club.
It was established with the help of Angeline Cross, who works at the prison advising female offenders on housing and benefits options after their release.
She is a member of another WI branch to ensure Bronzefield mirrors the events and agenda of a typical session.
She told the magazine WI Life: "During our meetings, the women forget that they're in prison and instead feel part of something that's really special, where learning new skills and getting to know new people offers a huge boost of confidence.
"Craft is really popular and our members loved getting involved in cutting out the lettering and hand-stitching the design for our first banner. Members are very proud of their WI being the first to be established within a prison."
One 28-year-old inmate named Gemma has been inspired to start her own bakery business on release after winning a WI baking contest.
She was able to present her winning cookie to Princess Anne, who was visiting the jail.
She said: "The most inspiring thing about being a member is being able to apply my new skills on the outside,' said Gemma. 'I can't wait to try out some new recipes for my Mum and possibly join a new WI after this.
"It's great that we have a mix of ages - we have different views and the older generation can pass on their skills to us. I don't want to miss a meeting for fear of missing out on something new."
Surrey WI adviser Jill Elliott said: "For those who are able to benefit, it's the opportunity to have some normality and an experience which we hope in many cases will continue for them in resettlement.
"It's about making a leap of faith and knowing that "together we can make a difference". The WI provides an opportunity to co-operate and share an experience - all things we take for granted outside prison."
Janice Langley, chairman of the national membership committee, added: "It has been a great privilege to witness the enthusiasm with which both members and the prison staff have welcomed us.
"I'd like to think that when members of Bronzefield are back in the community, they will find a WI somewhere that will be welcoming."