The 28-year-old, who earned £60,000 a week with Sunderland before he was sacked, will receive up to £15 a week while completing the rehab programme.
Once inside he will be encouraged to confront his crimes in both group and one to one sessions.
Johnson is expected to serve his time at HMP Frankland in Durham with other inmates like child killers Ian Huntley and Levi Bellfield but will not qualify for early release unless he can show parole officers he has completed the course and is genuinely sorry.
Former inmate Jermaine James suggested Johnson may have to pay inmates to protect him:
He may have to pay money to criminals to protect him. I am not suggesting he is going to do that, but it is a factor for him.