Niemi was claimed on Tuesday, a day after being waived by the Pittsburgh Penguins. He allowed 16 goals in losing three games for the Penguins. Niemi is now on his third team in four months and fourth since winning the 2010 Stanley Cup with Chicago.
He signed with Pittsburgh in free agency last summer after being released by Dallas in June.
The Panthers are at Montreal on Tuesday to close out a two-game road trip.