Neshek's deal is worth $16.25 million, a source told ESPN's Jerry Crasnick.
Neshek was 5-3 with a 1.59 ERA in 71 relief appearances combined with Colorado and Philadelphia last season. He held right-handed hitters to a .201 average and had 69 strikeouts in 62 1/3 innings.
A two-time All-Star, Neshek was traded from the Phillies to the playoff-bound Rockies for three minor league players midway through the season. He was an All-Star last year in his first season in Philadelphia.
Neshek, 37, has a 33-22 career record with eight saves, a 2.75 ERA and 447 strikeouts in 445 2/3 innings. He has pitched in 494 games -- all relief appearances -- for Minnesota, San Diego, Oakland, St. Louis, Houston, Philadelphia and Colorado.
Information from The Associated Press was used in this report.