The US reality star, 27, didn't reveal on the show why his mother was imprisoned, but local news records state Karen Armacost was sentenced to six years behind bars on theft and forgery charges.
According to Associated Press, as reported in the Indiana Business Journal, Karen was sentenced in June 2013 for stealing more than $680,000 from her employer.
A judge ordered Karen, then 53, to spend six years behind bars and three years on probation, after she pleaded guilty to theft and forgery, as well as trying to obtaining a controlled substance by fraud or deceit.
The court heard that Karen had been working for Greenwood Orthopedics, a medical practice in Franklin, Indiana, USA. She was accused of forging checks to herself between 2007 and 2012, and taking credit card payments from the practice.
Her employer discovered what was happening when she tried to obtain Vicodin through a forged prescription.
Austin spoke about his mother in the Diary Room as he tried to explain why he'd been so angry and emotional in the CBB house in recent days.
He said: "I have done nothing but be honest and truthful with everybody in this house and that is why from the start I wanted to share about my brother and my mum, because I'm f**king pissed off.
"I had to bury my brother and then send my mum to prison. I saw my mum for a week before I came to London and I come back to Huddersfield and see this amazing family that my husband has and that p*sses me off because my family is self-destructive and crumbled from within and that sh*t p*sses me off.
"Nobody can seem to realise that what I am going through. I am f**king angry and I'm sad and I am hurt by all of this, but for some reason everyone takes her side."
For exclusive competitions and amazing prizes visit Reveal's Facebook page NOW!