Ranaudo, 25, joined the Red Sox last season after he was named the International League's most valuable pitcher. In seven starts with the Red Sox, Ranaudo went 4-3 with a 4.81 ERA and 15 strikeouts to 16 walks.
The Rangers drafted Ranaudo in 2007, but he did not sign a contract and instead played college ball at LSU from 2008-10. The Red Sox drafted him as a supplemental first-round pick in the 2010 draft.
''He is a guy we like, we've liked for a long time,'' Texas general manager Jon Daniels said on a call from the Dominican Republic, according to the Associated Press. ''When this trade came down, we liked the value.''
Ranaudo is expected to begin spring training in competition for the Rangers' No. 5 starter job.
Ross, 25, spent the first three seasons of his MLB career with the Rangers. Last season, he went 3-6 in 27 games (12 starts) with a 6.20 ERA and 51 strikeouts to 30 walks.
He made nine of those starts in the first half of the season before he was moved to the bullpen. Over his career, Ross is 12-2 with a 3.27 ERA as a reliever, compared to 1-6 with a 5.70 ERA as a starter (all in 2014).
- Mike Fiammetta