She has mentioned in interviews about her parents ensuring their children received proper education and encouraging the six siblings to pursue careers of their own interest so that they can excel.

I am equally persevering and determined like my mother.”[4][3] Thomas studied in St. Michael's Higher Secondary School and St. Joseph's College for Women,Alappuzha.

She also received a scholarship that covered her tuitions fees having been entered into the first ten students of the merit list during her admissions.

[4][10] In both school and college Thomas was involved in extracurricular activities including political issues.

[10] She also pursued MBA in Operations Management and Ph.D. in guidance missile under the Defence Research and Development Organisation.

[14] Later, Tessy Thomas was appointed as the project director of the 5,000 km range Agni-V in 2009, which was successfully tested on 19 April 2012.

[1] She is a distinguished member at the Indian National Academy of Engineering (INAE), Institution of Engineers-India (IEI) and Tata Administrative Service (TAS).

[15] Thomas received the Lal Bahadur Shastri National Award for her contribution for making India self-reliant in the field of missile technology.