Grunwald, who has served as the interim GM since July 2011, was officially named the Knicks' executive vice president and general manager by team owner James Dolan.
"Glen has done a terrific job this season," Dolan said. "He is an intelligent, seasoned executive and we look forward to him continuing in the role of general manager for many years to come."
Before taking over as interim GM, Grunwald had been the team's senior vice president of basketball operations for five years. That followed 10 seasons working for the Toronto Raptors.
"It has been a great honor to be a part of this storied franchise for the past six seasons," he said.
The Knicks have posted a 34-30 record with two games to play this season and hold the seventh playoff seed in the Eastern Conference.
LGBT community has 'bullied the American people': Bachmann
Duggar sisters unveil Christian dating rules in new book