University deputy rector, Suebphong Chumuang, said the decision to suspend classes was made out of fear for students safety, since the motive for the deadly attack remained unclear.
The shooting occurred at a bus stop in front of the university's Osot Sala pharmacy in Pathumwan district on Tuesday.
A female student was killed while a male engineering student was wounded.
Chief investigating officer Pol Lt Col Phanom Chuathong said the shooting took place about 9.30pm.
The victims were among several people waiting at the bus stop, which is also close to Chulalongkorn University's pharmacy, he said.
The gunman stopped on a motorcycle near the bus stop and opened fire, according to eyewitnesses.
No spent shells from the shooting were recovered by officers, nor was the suspect caught on any nearby CCTV camera footage, Pol Lt Col Phanom said.