The Mets signed Bradley to a minor-league contract Tuesday, Michael Mayer of MetsmerizedOnline.com reports.
Bradley signed a contract with the independent league Long Island Ducks on Thursday.
The Royals waived Bradley on Friday.
The Royals designated Bradley for assignment Monday, Anne Rogers of MLB.com reports.
Bradley will start in center field and bat ninth in Sunday's game against the Nationals.
Bradley went 1-for-4 with a two-run home run in Monday's 8-5 extra-inning loss to the Tigers.
Bradley is out of the lineup for Sunday's game against the Brewers.
Bradley is not in the starting lineup for Wednesday's contest against the White Sox.
Bradley will start in center field and bat ninth in Sunday's game against the Athletics.
Bradley went 2-for-4 with a double and two runs scored in Sunday's 8-4 loss to the Twins.