Nieuwenhuis, 27, batted .079 for the Mets this season, with no home runs, two walks and 17 strikeouts in 38 at-bats. He is a career .230 hitter, with a .302 on-base percentage and .676 OPS.
The Angels have the lowest on-base percentage and OPS in the major leagues. Their left fielders -- in the position manned last year by the banished Josh Hamilton -- are batting .173 with one home run.
Nieuwenhuis, who bats left-handed, was designated for assignment by the Mets last week. The Mets selected him from Azusa Pacific in the third round of the 2008 draft.
He would figure to compete with fellow left-handed hitters Marc Krauss and Efren Navarro on the Angels' depth chart.