Liina Tennosaar was born on May 23, 1965, in Tallinn, Estonia, to Kalmer Tennosaar and Sirje Tennosaar (née Arbi). Her father was a well-known Estonian journalist, singer, and television personality, who hosted the popular children's television series Entel-Tentel. Her mother was also a stage, film, and television actress.
Liina attended primary and secondary schools in Tallinn, graduating in 1982, before studying acting at the Tallinn State Conservatory, Performing Arts Department, which is now known as the Estonian Academy of Music and Theatre. She graduated in 1986.
Tennosaar made her television debut at the age of 22 in the 1983 comedy television feature-length film Püha Susanna ehk meistrite kool, directed by Ago-Endrik Kerge. She has since appeared in numerous television series and films, including Õnne 13, Urpo & Turpo, Ohtlik lend, Ühikarotid, Kelgukoerad, Kättemaksukontor, Elu keset linna, and Viimane võmm, as well as the TV3 mystery-drama series Merivälja.
In addition to her television work, Tennosaar has appeared in several feature films, including Sügis, Hysteria, Sügisball, Jan Uuspõld läheb Tartusse, Taarka, Vasha, Deemonid, and Asjad, millest me ei räägi. She has also appeared in numerous film shorts and student films.
