The team said it finalized the deal Friday.
Carroll's agent, Jonathan Maurer, said the deal includes incentives up to $525,000 a year based on at least 275 plate appearances.
Although Oakland offered more money and playing time, Maurer said Carroll wanted to play for Dodgers manager Joe Torre and coach Don Mattingly, who is from Carroll's hometown of Evansville, Ind.
The Dodgers have penciled in Blake DeWitt as the starting second baseman.
"Jamey has said he looks to partner with Blake DeWitt and form a tremendous 1-2 punch at second base to help this team get back to the playoffs," Maurer said.
The 36-year-old Mientkiewicz dislocated his right shoulder while sliding into second base for a double on April 16, went on the disabled list and wasn't activated by the Dodgers until Sept. 2. He was just 6 for 18 with three RBIs last season.
Berroa, who turns 32 next month, hit .148 with two RBIs in 27 at-bats for the New York Mets last season. If added to the 40-man roster, he would get a split contract calling for salaries of $600,000 in the majors and $81,000 in the minors.
Towers, a 32-year-old right-hander, had no record and a 3.38 ERA in two relief appearances for the Yankees this year. He would get $700,000 in the majors and $100,000 in minors if added to the 40-man roster.