An official at the State Correctional Institution in Chester, PA tells TMZ ... the rapper was just transferred to their prison and out of Camp Hill. He's now in general population and he has his own cell.

We broke the story ... Meek wanted out of solitary because he feared it would take a severe toll on his mental state.

Meek can now hit up the yard in the morning or afternoon. He can ball out on the court or go for a jog. Should he fancy himself with a book, he can read it at the on-site library or in his cell. Gym time will depend on which job he ends up taking ... which, by the way, pays 19 cents an hour.