Johnson was selected first overall in the 1991 NBA draft by the Charlotte Hornets, and won the NBA Rookie of the Year Award in his first season. He also competed in the 1992 Slam Dunk Contest at the NBA All-Star Weekend in Orlando, finishing second to Cedric Ceballos of the Phoenix Suns.
In 1993, Johnson was voted to start in that year's All-Star Game, making him the first Hornet in franchise history to receive that honor; he enjoyed his best statistical season with averages of 22.1 points per game and 10.5 rebounds per game in 82 games, which earned him All-NBA Second Team honors. Along with Alonzo Mourning, Muggsy Bogues and Dell Curry, Johnson played with the Hornets at the height of their popularity in the early to mid-1990s. During this time, Johnson, who went by his initialism "LJ" and the nickname "Grandmama" (because of a popular series of commercials for Converse, who signed Johnson to an endorsement contract following his entry into the NBA), was featured on the cover of the premiere issue of SLAM.
In October 1993, Johnson signed what was at the time the most lucrative contract in NBA history, a 12-year, $84 million deal with the Hornets.[7] However, he missed 31 games after spraining his back on December 27, 1993 in a game against the Detroit Pistons. During the summer he played for the U.S. national team (nicknamed Dream Team II) in the 1994 FIBA World Championship, winning the gold medal.[8]
Johnson had entered the league as an explosive power forward, averaging over 20 points and 10 rebounds per game. However, after the injury to his back, Johnson was forced to develop an all-around game with an improved outside shot. In the 1994–95 season, he made 81 three-pointers, nearly 60 more than in his first three years combined, and was selected to the 1995 NBA All-Star Game.[9]
Friction between Johnson and Mourning forced the organization to make a change, and the resulting moves made by the Hornets left both players on other teams. Prior to the 1995–96 season, Mourning was traded to the Miami Heat for Glen Rice and Matt Geiger. Following that season, Johnson was dealt to the New York Knicks for Anthony Mason and Brad Lohaus.