Holownia's work has been shown in numerous exhibitions. He was featured in solo shows at the Centro de la Imagen (Mexico City), McCord Museum (Montreal, PQ), the Art Gallery of Nova Scotia (Halifax NS), the Owens Art Gallery (Sackville NB), the Dunlop Art Gallery (Regina SK), the Confederation Art Gallery (Charlottetown), the Jane Corkin Gallery (Toronto ON), and the Art Gallery of Hamilton, the McMichael Canadian Collection, (Kleinburg, ON) and the Tsongas Gallery (Concord MA) among others. His photographs have been included in many group exhibitions including Monet's Legacy: Series, Order and Obsession (Hamburger Kunsthalle), Before the Land, Behind the Camera (Canadian Museum of Contemporary Photography), The Landscape: Eight Canadian Photographers (McMichael Canadian Collection), Exposure (The Art Gallery of Ontario), and Photo Perspectives (Presentation House, Vancouver).

Photographic prints and bookworks by Thaddeus Holownia are in the collections of the National Gallery of Canada, (Ottawa), Yale University (New Haven), the Canadian Centre for Architecture (Montreal), the Museum of Fine Arts (Houston Texas), the Canadian Museum of Contemporary Photography (Ottawa), and many other corporate, public and private collections.

Thaddeus Holownia has been the recipient of grants and awards from the Canada Council for the Arts, the Ontario Arts Council, the American Institute of Graphic Arts, the Royal Canadian Academy for the Arts, the Social Sciences and Humanities Research Council, the Crake Foundation and the Marjorie Young Bell Research Foundation. A dedicated teacher he has been a four-time recipient of the Mount Allison Paul Paré Award for Excellence and was awarded the Paul Paré Medal in 1998 for excellence in Teaching, Research/Creative Activity and community service. In 2001, Holownia was awarded a Fulbright Fellowship by the Fulbright Foundation of Washington, DC, and in 2003 he received the Strathbutler Award from the Sheila Hugh McKay Foundation of Rothesay, New Brunswick.