Martinez (thumb) signed a minor-league deal with the Red Sox on Saturday, Chris Cotillo of The Springfield Republican reports.
Martinez joined the Giants on a minor-league deal in mid-March after missing most of last season with a torn thumb ligament. He didn't make the major-league roster and was released in late April without having pitched at any minor-league affiliate. It's unclear whether or not he's fully recovered from his thumb injury, so it's unclear whether he'll pitch for a Red Sox affiliate right away.