Jett’s basket with 35 seconds remaining broke a 61-61 tie, and Ellis made four free throws to keep the Billikens (5-3) in control and give them back-to-back victories for the first time this season.
Saint Louis has won both of its games since the death of coach Rick Majerus, who stepped down before this season and was replaced by Jim Crews. Majerus died Saturday in Los Angeles.
Chris Jones led the Mean Green (3-6) with 21 points. Tony Mitchell had 18 points and eight rebounds for North Texas, which has lost four in a row.
It was the teams’ first meeting since 1981.