Chinnathambi Malesan was on his way to his dormitory on December 8 last year when he saw a crowd of rioters pelting projectiles near Race Course Road in the precinct of Little India.
Malesan joined the rioters and threw a palm-sized piece of concrete at the bus, the court heard. He then took photos of the bus with his mobile phone to show his friends back at the dormitory.
Pleading for a lighter sentence, lawyer R Kalamohan, who is defending him pro bono, said Malesan had readily admitted to his involvement.
Kalamohan added Malesan had not consumed alcohol that night. He also pointed out that Malesan's employer had faith in Malesan's character and even offered to bail him out with SGD20,000 after he was detained following the riot.
The Little India Riot saw 23 emergency vehicles being damaged, five of which were completely gutted.
The damage to police vehicles amounted to more than SGD 630,000 and 54 responding officers were also injured in the riots.
Damage to the private buses was estimated to be more than SGD38,000.
The riot was sparked by a fatal accident involving a bus and an Indian national who was working in Singapore.
Some 400 migrant workers were at the scene of the riot. Fifty-two Indians were deported from Singapore for their alleged involvement in the riots.
Twenty-five Indian nationals, working in Singapore on permits, were charged for rioting.
Little India is a precinct of Indian-origin businesses, eateries and pubs where most of the construction workers from South Asia spend their weekend and day off.
Most of the rioters were reportedly drunk on the night of the riots.
Malesan became the 21st person to be sentenced. He could have received a maximum sentence of seven years.