Santhushi holds a Bachelor of Laws (Honours) degree from the University of Colombo and is currently reading for a Master of Laws (LLM) by Research, specializing in Commercial Law, at the University of Colombo. After successfully completing the final examination for the admission of attorneys-at-law conducted by the Sri Lanka Law College, she was admitted and enrolled as an attorney-at-law of the Supreme Court of Sri Lanka in December 2023. She currently practises as an attorney-at-law, a notary public, and a company secretary.

Santhushi has experience in the legal field in various capacities as a practising attorney, legal researcher, and academic. She began her career as a legal intern at a well-known president's counsel's chamber, followed by a legal apprenticeship at the attorney general's department, where she gained experience in legal document preparation and trial preparation. She then worked as an enumerator on the USAID Efficient and Effective Justice (EEJ) Project at Chemonics International before working as a legal associate, where she handled legal document preparation and commercial contract review.

Alongside her legal practice, Santhushi has built an academic career, starting as an Assistant Lecturer (Temporary) at the University of Sri Jayewardenepura. She went on to serve as a visiting lecturer at the Sri Lanka Institute of Information Technology (SLIIT) and Wayamba University of Sri Lanka. Building on this experience, she now works as a full-time lecturer in the School of Law, where she teaches civil and commercial law subjects to undergraduate law students.

• Master of Laws (LLM) by Research, specializing in Commercial Law, University of Colombo, Sri Lanka (2024–present)
• Attorneys-At-Law Final Examination, Sri Lanka Law College, Sri Lanka — Second Class Honours, 2022–2023
• Bachelor of Laws (Hons) (2nd Class – Upper Division), University of Colombo, 2018–2022
• Certificate Course in Human Resource Management, Institute of Personnel Management, Sri Lanka — Merit, 2018
• GCE Advanced Level, Bishop's College, Colombo — 4A's, 2017
• GCE Ordinary Level, Bishop's College, Colombo — 9 A's, 2014

• Best A'Level Arts Student Prize, Bishop's College, Colombo, with multiple subject prizes (2015/2016)
• Higher Distinctions (A) at GCE A/Ls (2017)
• Best O'Level Results Prize for outstanding academic performance, Bishop's College, Colombo (2014)

• Corporate Law
• Employment Law