Thatcher agreed to a minor league contract with the Cubs on Monday, Chris Cotillo of SB Nation reports.
Thatcher, released by the Indians last week, will report to Triple-A Iowa as he attempts another return to the majors. The 34-year-old posted a 3.60 ERA over 15 innings for Triple-A Oklahoma City earlier this season and will provide depth for a Cubs bullpen that's carrying just three left-handed relievers.