Lakers general manager Rob Pelinka announced the move on Tuesday, after Nwaba's second 10-day contract expired.
Nwaba was promoted from the Lakers' D-League affiliate on Feb. 28, and he immediately caught on with standout defense and steady play. He is averaging 3.6 points and 2.0 rebounds in 10 games for the Lakers, including two starts.
"He gives us a toughness that we definitely need," Lakers coach Luke Walton said. "He gives us a defensive mindset that we definitely need. It's nice to be able to preach something all day, every day, in practice and in games, and then have a young guy that's hungry -- and whether he plays at all in the first three quarters [or not], when he steps on the court, he's ready to compete. He's ready to get after it on defense."
Pelinka said the Lakers also like Nwaba's work ethic in practice.
Nwaba is a product of Los Angeles' University High, Santa Monica College and Cal Poly-San Luis Obispo.
Information from ESPN's Baxter Holmes and The Associated Press was used in this report.