Theresa Markiw was born in Montreal, Canada of Ukrainian emigres and grew up in New Jersey. She began studying at the Philadelphia Museum of Art at the age of eight, followed by a decade at the Barn Studio of Art in Millville, NJ, with renowned marsh painter and mentor Pat Witt. While at "the Barn," Theresa studied with many visiting artists, including Morris Blackburn, Oliver Grimley, Chinese brush painter Phoebe Shih, and iconographer Piedman Shofronoff. In 1979 Theresa received a BFA from Concordia University in Montreal.

Theresa worked for ten years in advertising and graphic design in New Jersey, then moved to Washington, DC, where she worked for the National Endowment for the arts, Voice of America, US Information Agency, and Department of State. She served at US Embassies in Mongolia and Azerbaijan as Public Affairs Officer, with arts and culture as part of her portfolio. In Mongolia she worked to establish the Arts Council of Mongolia, and received an honorary Doctorate from the Mongolian Academy of Sciences.

In 2006 Theresa left the diplomatic service to join her university professor husband in Tennessee and devote herself full time to painting. In 2018 she and her husband moved to the Shenandoah Valley of Virginia, where she continues to paint and exhibit.

Throughout her career, Theresa has pursued a parallel life as a professional artist, exhibiting in over 80 solo and group shows in the US, Canada, Ukraine, and Azerbaijan. In 1993 she was selected to be part of the 2nd Annual International Artists Symposium in Ukraine, traveling and painting for two months with an international group of artists. The Symposium culminated with an exhibition in Ukraine's capitol Kyiv, which then traveled around the country.

Her work is in collections in the US, Canada, and around the world.