Ex-nurse Marjorie Blackadder, 62, has spent thousands of pounds of her savings over the past five years on her son, Christopher, 23.
In an interview with GMTV, the regular churchgoer, who lives in Carlisle, Cumbria, said: "We had a discussion and he genuinely wants to get off heroin but has great problems. So I did a deal with him. I said that I would actually monitor his use of heroin to try to help him reduce his intake each day and I have been doing that.
"I actually give him the money and take him in the car. I don't know where he goes. He goes and gets the heroin and he comes back home and he takes it.
"Since February I have been able to reduce him from taking half-a-gramme of heroin a day and hopefully today is going to be the first day free of heroin."
Mrs Blackadder, who says she has had the support, to a certain degree, of her family and friends added: "I am actually keeping him healthy, I am keeping him safe, keeping him out of trouble and probably saving the country some money because the police aren't involved any longer.
"Yes, it is difficult to justify it, but at the end of the day I love my son and do feel it is my responsibility.
"It's not society's responsibility to support my son. It's my responsibility to help him get better and that's what I'm trying to do."
Mrs Blackadder has said she believes "morally and religiously" she could not allow her son to steal to afford his pounds 20-a-day addiction. She said she could not abandon him and and that the decision to support him was the lesser of two evils.