Aruni was crowned Miss Sri Lanka for Miss Universe 2007 and represented Sri Lanka at Miss Universe 2008. She was among the top fifteen finalist at the 47th Miss International 2007 held in Japan. She represented Sri Lanka in the 58th Miss Tourism Queen International 2007 in China and won the mini titles Miss Friendship along with the regional title Miss Oceania 1st runner-up. She participated in the second edition of Bride of the World pageant and was crowned as the second runner-up in Macau, China.
Aruni hosted the morning show ‘Hello Sri Lanka’ and the women’s program ‘Liyasevana’ at Swaranvahini from 2008 to 2011. She returned to Swarnawahini in June 2020 to host the relaunched breakfast show ‘Ayubowan Sri Lanka’. She was a household favorite while presenting Hiru TV travel show ‘Niwaduwata Travel Ekak’, and sociological and legal program ‘Mang Hinda Oba’.