He repaid the faith by winning the All Island Best All Rounder Award during his final year at St. Benedict's College.

[3] After having impressed with the ball at school level, he was called for trials by the National Cricket Academy at R. Premadasa Stadium.

[5] He was also omitted from Sri Lankan U-19 squad for the 2018 Under-19 Cricket World Cup on the basis of fitness issues.

[7] Theekshana made his List A debut for Colts Cricket Club in the 2017–18 Premier Limited Overs Tournament on 14 March 2018.

[10] He joined Sri Lanka Army in 2020 and transformed him completely as he began adhering to strict food diets and worked hard on improving his fitness levels.

[11] He initially didn't make the cut for the 2020 Lanka Premier League draft and he was categorized in supplementary category which made him ineligible to play.

[19] In August 2022, he was picked up by Johannesburg Super Kings for the inaugural edition of the South Africa's CSA T20 League which was held in 2023.

[29] Later the same month, Theekshana was named in Sri Lanka's squad for the 2021 ICC Men's T20 World Cup.

[36] Along with Wanindu Hasaranga, Theekshana made the spin bowling department, where Sri Lanka eventually won the tournament for the sixth time.

[39] The fans of Chennai Super Kings expressed their grief and vent their frustrations in disbelief by trending hashtags #Boycott_ChennaiSuperKings and #DontNormalizeTamilGenocide in various social media platforms soon after Chennai Super Kings bought Theekshana during the 2022 IPL auction since he had served in the Sri Lankan army.