Paul Ciancia, 23, entered the plea for 11 felony charges, including murder and attempted murder, during a brief court appearance.
Trial for the Sun Valley man is set for February 11 in Los Angeles federal court and prosecutors will seek the death penalty if Ciancia is convicted.
According to authorities, Ciancia opened fire with a semiautomatic rifle inside Terminal 3 at LAX.
They said Ciancia was specifically targeting TSA officers as he shot his way past a security checkpoint and into the gate area.
TSA agent Gerardo Hernandez, a 39-year-old father of two, was killed. Two other TSA officers and a teacher from Calabasas were injured.
Ciancia was arrested following a gunfight with airport police, who shot him four times.
He spent more than two weeks at Ronald Reagan UCLA Medical Center before he was released into the custody of the U.S. Marshals Service.
Ciancia remains in jail without bail.
City News Service contributed to this report.