Aaron Hernandez Will Get Out of Prison, Says His Lawyer Jose Baez

Aaron Hernandez will NOT spend the rest of his life behind bars ... so says his attorney, Jose Baez, who tells TMZ Sports he believes he can overturn the ex-NFL star's murder conviction.

Baez represented Hernandez in his double murder case -- but he was NOT on the team when Aaron was convicted of murdering Odin Lloyd, for which AH was sentenced to life in prison.

But Baez says he truly believes Aaron is innocent -- and says he hopes Hernandez will hire him to fight the conviction because he knows he can win.

"Nothing would make me happier than to prove everybody wrong."

The big question ... can Hernandez afford Baez? The short answer, no.