The decision came two days after Porzingis tore his left ACL and just a couple of hours after the NBA trade deadline. The Hornets reportedly had been shopping Walker in the days leading up to the deadline but opted to hang on to their franchise cornerstone.
The NBA also said that Detroit All-Star center Andre Drummond will replace Porzingis in the Skills Challenge. Porzingis is the event's defending champion.
Walker will be making his second All-Star appearance; he also played in last year's game.
This season, the former UConn star is averaging 22.6 points, 5.8 assists and 3.4 rebounds.
The 2018 All-Star Game will be held Feb. 18 at the Staples Center in Los Angeles.