Nieto, 47, had spent the past three seasons as the team's catching instructor.
"Tom is a knowledgeable baseball man, and I know he will do a great job for us," manager Willie Randolph said in a statement. "He has experience on the bases, and we will have the added bonus of having him in the dugout between innings so he can interact with the players more, especially our catchers Brian Schneider and Ramon Castro."
Nieto first worked alongside Randolph when he spent two years as the Yankees' catching coach at the start of this decade. Randolph was the team's bench coach at the time, and while the arrangement lasted only two years -- Nieto eventually took a job managing Class A Palm Beach of the Florida State League in 2003 -- the two were reunited with the Mets in 2005.
Before that, Nieto served as the manager of several Yankees farm teams, compiling 570 career wins as a Minor League manager.
His playing career lasted for only parts of seven seasons, and produced a .205 average and five home runs. Serving primarily as a backup catcher, Nieto won a World Series title with the Twins in 1987 and a National League pennant two years earlier with the Cardinals.
"I am looking forward to the change," Nieto said in a statement. "Every year I managed in the Minors I coached third, so being on the bases is nothing new. Also, being on the bench will help me assist the catchers with the game management. I think it is going to be an ideal situation."
The team sees that last part -- helping the catchers -- as more than just a bonus. It's no secret that the Mets have had an eye toward fortifying their defense behind the plate this winter, and they believe they've found an attractive tandem in Schneider and Castro. If Nieto can help both of them fulfill their defensive potential behind the plate, then his role may assume an added impact.
At the least, he'll attempt to add some stability to the first-base box after Henderson spent just half a season in the role. Nieto joins a coaching staff that includes incumbent third-base coach Sandy Alomar, pitching coach Rick Peterson and hitting coach Howard Johnson.
Anthony DiComo is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.