Martin, 35, averaged 5.2 points, 4.3 rebounds and 1.0 blocks in 22.4 minutes over 42 games with the Los Angeles Clippers last season. If he's in shape, Martin could help the Knicks' interior defense and boost their rebounding.
"We've always liked Kenyon," Knicks general manager Glen Grunwald said Thursday. "He's a great competitor and a good defender and he's played with a number of our players on the Knicks (including Carmelo Anthony and J.R. Smith). ... We're just looking forward to adding another good defender who can help us in our quest this season."
Prior to the trade deadline, the Knicks had expressed interest in signing a veteran big man, due to uncertainty surrounding the health of Rasheed Wallace and Marcus Camby.
Grunwald said he's hopeful that Wallace and Camby can return this season, but called Martin "insurance" if those veteran bigs can't get back on the floor.
Wallace has been out since mid-December with a stress reaction in his left foot. Camby has been sidelined since mid-January with a plantar fascia injury in his left foot.
There is no specific timetable for either player's return.
"Signing Kenyon is a bit of insurance for our bigs in case these tricky injuries continue to trouble Rasheed and Marcus," Grunwald said. "(Martin's) a versatile defender and can play and defend three positions in the NBA. It gives us a little bit more depth and more insurance."
Grunwald hopes the Knicks can extend Martin's deal for the remainder of the season.