Porzingis had been listed as questionable prior to Friday morning's decision and was awaiting clearance from team doctors.
Hornacek told reporters at the team's shootaround in Milwaukee that the Knicks will consider placing Porzingis on a minutes limit as New York plays the first game of a back-to-back.
Porzingis' Achilles soreness first surfaced after the Knicks' loss to the Boston Celtics on Christmas. The Knicks (16-19) have lost all three games without Porzingis and have dropped six in a row overall.
In his second season, Porzingis has been an integral player for New York on both sides of the ball, averaging 20.1 points, 7.9 rebounds and 1.9 blocks per game.