Sandra, who shot to fame after appearing the on the Channel 4 show alongside her best friend Sandi Bogle, served time in 1984.
Speaking about her stint inside for the first time, the 54-year-old says she “deeply regrets’ what she did.
“It was a very long time ago and I deeply regret it,” she told The Sun on Sunday.
Sandra also strongly denied accusations that she bullied another inmate during her time in prison.
An unnamed fellow inmate at Drake Hall prison in Staffordshire alleges Sandra was “scary from the word go” and “made my time at Drake Hall horrific.”
But Sandra denied she was a bully, saying: “I strongly refute any accusations of bullying. It didn’t happen.”
A spokesman for Channel 4 said they were aware of Sandra’s past conviction but had no further comment.
“We do not comment on the private lives of individuals,” the spokesperson told the newspaper.
“We have been aware of Sandra’s spent convictions since we began filming with her, which relate to non-violent offences.”
Sandra is still a firm favourite with fans of ‘Gogglebox’, but last year her longtime sofa pal Sandi was replaced by Sandra’s daughter Chanchez.
The pair - who have been friends for over 40 years - first appeared on Gogglebox back in 2013, but Sandi decided to take a break from the show to pursue a music career.
Addressing rumours that she had fallen out with Sandra, Sandi said: “Me and Sandra were best friends long before ‘Gogglebox’ and we always will be, simple as.
Addressing a potential return in the future, Sandi added: “They’ve left the door open for me to return so there are no hard feelings.”