The Panthers extended their winning streak to three games behind 19 saves from Theodore. All three wins have come at home and all have been by a single goal.
Jason Garrison, who leads NHL defensemen in scoring with eight goals, tallied on the power play midway through the first period.
Kris Versteeg gave the Panthers a 2-0 lead 1:09 into the second and Derek Stepan produced New York's only goal 3 minutes later.
Henrik Lundqvist was the hard-luck loser, making 35 saves. The Rangers have dropped two in a row after winning seven straight.