"Tin-Tin" is the second of four children in the family. Her ethnicity is Spanish/Chinese/Filipino, her mother being of Spanish descent and her father being Chinese Filipino. For her screen name, she used her mother's maiden name "Hermosa" (which translates to "beautiful" in Spanish).
On September 21, 2004, she married actor Diether Ocampo. Their marriage ended shortly after and was officially annulled on January 30, 2009.
She married actor and host Oyo Sotto on January 12, 2011. They have four children
Hermosa was discovered at age 12 when her older sister Kathleen auditioned for a show in ABS-CBN. She was cast in the 1998 weekly drama series, Sa Sandaling Kailangan Mo Ako. In 2000, she was cast in the primetime soap opera, Pangako Sa 'Yo. She starred in the film Forevermore, released in 2002. In 2003-04, she starred in Sana'y Wala Nang Wakas.
She also played the lead role in the short-lived television series 'Til Death Do Us Part in 2005. Hermosa appeared in Gulong ng Palad and Prinsesa ng Banyera in 2006 and 2007 respectively and in 2009 in Dahil May Isang Ikaw.
Her last project on ABS-CBN before moving to GMA Network was the action-fantasy series Noah where she played a diwata, the counterpart of a fairy in Philippine mythology.
In 2016, she was part of GMA Network's weekly sitcom "Hay, Bahay" with her husband Oyo Boy Sotto, Vic Sotto and Ai-Ai delas Alas