The contract, which will be finalized with the completion of a physical, also includes two team options that, if exercised, would increase the value of the deal to $52 million. The Mets will forgo four years of team control over Niese.
The source indicated that the deal was structured similarly to the five-year, $28.5 million deal the Rangers executed with Derek Holland. Niese, like Holland, would have been a free agent following the 2015 season.
The 25-year-old Niese enters his third full season with the Mets. The club's seventh-round pick in the 2005 First-Year Player Draft is coming off a year in which he went 11-11 with a 4.40 ERA, recording 138 strikeouts over 157 1/3 innings before a right intercostal strain in August cut short his season. Niese, who made his big league debut on Sept. 2, 2008, has posted a 22-23 record and 4.39 ERA in 64 career starts and one relief appearance.
There had been speculation earlier this week that a deal was in the works for Niese. The left-hander had an up-and-down showing during Spring Training, posting a 5.73 ERA over six games (five starts). He ended his spring on Tuesday against the Yankees, giving up five earned runs on eight hits across 1 2/3 innings in a relief appearance.
Jon Star is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.