Having completed her secondary education at the Good Shepherd Convent, Colombo, she enlisted in the Sri Lanka Navy as a seaman recruit in 2011 and specialized in communicator trade.

[4] She was awarded the bronze medal in the women's 50m rifle 3×20 event representing Sri Lanka Navy at the 2016 National Shooting Sports Federation.

[6][7][8] She represented Sri Lanka at the 2016 South Asian Games at a time when she gave birth to her twin baby sons.

[11] She was selected for the postponed 2020 Summer Olympics,[12][13] competing in the women's 10m air rifle 0.1777 event in the shooting category representing Sri Lanka.

[16] Tehani was the third Sri Lankan athlete to be selected for the 2020 Tokyo Olympics after Mathilda Karlsson and Milka Gehani.