The Hornets are Amundson's third NBA team this season. The 6-foot-9 former UNLV standout opened the 2012-13 season with the Minnesota Timberwolves, who waived him early last month. He then joined the Chicago Bulls on a 10-day contract but appeared in only one game.
Amundson has appeared in 21 games this season, his seventh in the NBA, averaging 1.5 points and 2.3 rebounds in 7.8 minutes.
The Hornets were seeking an experienced reserve front court player to fill the void left by Jason Smith's season-ending shoulder surgery.
Sims was signed to a 10-day contract March 3 and appeared in two games.
New Orleans plays at Brooklyn on Tuesday night.