A source confirmed to ESPN.com that the Rangers signed Boyle to a two-year, $9 million contract, which also includes a no-move clause.
The 37-year-old Boyle, a long-time member of the San Jose Sharks, was one of the most coveted defensemen to hit the market when free agency opened.
A source told ESPN.com that Boyle left money on the table as he thought the Rangers were the best fit and gave him the best chance of winning in the short term.
The Rangers lost in the Stanley Cup finals to the Los Angeles Kings earlier this month.
For the Rangers, Boyle fills an immediate need on defense with the departure of unrestricted free agent Anton Stralman to the Lightning. Boyle also can provide the team with the type of power-play quarterback they have been seeking in recent years.
The Rangers also expressed interest in acquiring Boyle at the trade deadline last year.