Spencer-Nairn was born in Montreal, Quebec, but raised in Vancouver, British Columbia. She is a graduate of the Vancouver Film School.
Spencer-Nairn has appeared in a number of film and TV productions since the mid-1990s. Some of her most notable film appearances include New Waterford Girl, Wishmaster: The Prophecy Fulfilled, and television guest appearances on Puppets Who Kill, Relic Hunter, Cold Squad, Bliss, Flashpoint, and The Outer Limits. In 2005, she portrayed Wayne Gretzky's sister Kim Gretzky in the movie Waking Up Wally: The Walter Gretzky Story.
Her most notable roles are Constable Karen Pelly on Corner Gas and Sandy Wardwell on CTV's "The Listener." Concurrent to appearing in Corner Gas, she also appeared on the science fiction series "ReGenesis."
Spencer-Nairn married Josh Glover in 2008. Together, they have sons Foster (born 2011) and Carson (born 2014).