The Mets signed Brosseau to a minor-league contract Tuesday, Michael Mayer of MetsmerizedOnline.com reports.
Brosseau signed a minor-league contract with the Royals on Thursday.
Brosseau cleared waivers and was outrighted to Triple-A Nashville on Sunday, Adam McCalvy of MLB.com reports.
Brosseau was designated for assignment by the Brewers on Wednesday.
Milwaukee optioned Brosseau to Triple-A Nashville on Monday.
Brosseau went 1-for-1 with a solo homer in Sunday's win over the Royals.
Brosseau is not in the lineup Tuesday night at Colorado.
Brosseau is starting at third base and batting eighth Sunday against the Padres, Todd Rosiak of the Milwaukee Journal Sentinel reports.
Brosseau went 2-for-4 with a double, a home run and three RBI in Tuesday's victory over the Diamondbacks.
Brosseau, per Adam McCalvy of MLB.com, secured a spot on the Brewers' Opening Day roster.