The person requested anonymity Tuesday because the team was not ready to make the announcement. Thome's contract also includes performance bonuses.
The 39-year-old Thome will likely be more of a bench player for the Twins than the middle-of-the-lineup force he's been for 19 seasons on his way to 564 career home runs.
Thome was traded by the White Sox to the Los Angeles Dodgers on Aug. 31. He was interested in returning to Chicago, but White Sox manager Ozzie Guillen recently told Thome he wouldn't get enough at-bats to justify a return.