Catherine was born to Malayali Roman Syrian Catholic parents Frank Mario Alexander and Tresa Alexander. She did her Class 12 in Dubai and moved to Bengaluru for higher education. She studied for two years in St Joseph's College, Bengaluru. While studying, she pursued extra-curricular activities like piano, singing, dancing, ice skating and debating. She had participated with Prasad Bidapa in many ramp shows in many cities.
Catherine Tresa made her acting début in 2010 Kannada film Shankar IPS. Catherine went on to act in the Malayalam films, The Thriller and Uppukandam Brothers Back in Action. Her performance in God Father, earned her first nomination for an award in the Best Supporting Actress category at the 60th Filmfare Awards South. She next appeared in Paisa by Krishna Vamsi . In 2014, she made her foray into the Tamil film industry with Madras for which she received many awards. She also enacted in Kanithan, Rudhramadevi, Kathakali. Her upcoming movies are Sarrainodu, 24, Thani Kattu Raja, Kaan. After coming to India, she modelled for Nalli Silks, Chennai Silks, Fast Track, Josco Jewellers and Deccan Chronicle.