Terms of the deal weren't announced, but ESPN reported it was worth $52 million, including an $8 million signing bonus and annual salaries of $11 million per year.
Jackson, 29, compiled a 10-11 record with a 4.03 earned run average last season with Washington.
The 10-year veteran boasts a 70-71 career mark with a 4.40 ERA and tossed a 150-pitch no-hitter in 2010 while with the Arizona Diamondbacks.
Jackson has also pitched for the Los Angeles Dodgers, Tampa Bay, Detroit, the Chicago White Sox and St. Louis.
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