With Chris Paul out for months at two separate times during the 2009–10 season, Collison became the starting point guard. Collison handed out a Hornets rookie-record 18 assists and scored 17 points on January 30, 2010 when New Orleans ended Memphis's 11-game home winning streak with a 113–111 overtime victory. Later on March 8, 2010, Collison broke his own record with a Hornets rookie-record 20 assists (along with 16 points) in a 135–131 victory over the Golden State Warriors. In a game against the Indiana Pacers on February 19, 2010, Collison became only the second rookie of the 2009–10 season to get a triple-double with 18 points, 13 rebounds, and 12 assists. He finished 4th in the NBA Rookie of the Year voting and averaged 18.8 points and 9.1 assists in the 37 games as a starter, but had four turnovers a contest as a starter in his first NBA season.
On August 11, 2010, the Hornets traded Collison and James Posey to the Indiana Pacers in a four-team, five-player deal that also sent Troy Murphy to the New Jersey Nets, Trevor Ariza to the New Orleans Hornets and Courtney Lee to the Houston Rockets.