The Rangers have won three in a row, the last two coming against the Islanders. The teams played Wednesday at Yankee Stadium with the Rangers winning 2-1.
It was a 1-1 game heading into the third period, but Brassard scored the deciding goal with 7:46 to play. Richards soon followed with his 14th of the season and Ryan McDonagh had an empty-net goal with a second remaining.
The Islanders lost their fifth in a row.
Evgeni Nabokov surrendered three goals while making 33 saves.