The England international has not played for Sunderland since he was arrested and later bailed on suspicion of sexual activity with a 15-year-old girl at the start of this month.
Durham Police extended Johnson's bail until April 23 on Tuesday, with Sunderland stating that his suspension was under review.
Sunderland have now confirmed that the club have liaised with the Professional Footballers' Association and Johnson's representatives.
Subsequently it has been agreed that Johnson will be allowed to continue his duties with the club and will resume training.
Durham Police have stated their investigation remains ongoing
"Sunderland AFC informed us this morning of their decision, which of course is a matter entirely for the club," read a Durham Police statement.
"The police investigation remains very much live and ongoing and a man remains on bail while enquiries continue.
"We would once again urge those posting on social media to be aware of the effects their comments can have. We accept rumour and speculation may be inevitable, but many of the comments have been distressing to the complainant, her family and people connected with the investigation."
