Denis began her broadcasting career at a local radio station in
Moscow, Idaho, and later moved to
Calgary where she worked at
CHFM-FM &
CJAY-FM. In addition, she was a sports and entertainment reporter and weather announcer at
CFCN-TV and
TSN. Since July 2, 1986, Denis has been one of the co-hosts of
CHUM-FM's morning show. Originally titled
Roger, Rick and Marilyn, co-hosting with Roger Ashby and Rick Hodge, then
Roger and Marilyn after the departure of Hodge in June 2008 (Hodge's replacement, Darren B. Lamb, departed from the station in September 2015) until Ashby's retirement in December 2018. Denis currently hosts the morning drive slot on CHUM-FM titled
The Marilyn Denis Show from 5 a.m. to 9 a.m. with co-host David Corey, who joined the show on September 16, 2024. From September 5, 1989 to May 23, 2008, she also hosted the syndicated daytime
talk show CityLine on
Citytv and
A-Channel. With the
CTVglobemedia purchase of
CHUM Limited, and the subsequent sale of five Citytv stations to
Rogers Media, mandated by the
Canadian Radio-television and Telecommunications Commission, Denis temporarily found herself working for two separate media competitors. To resolve this situation, Denis announced that she would be leaving
Cityline after 19 years to pursue current and future projects with the
CTV Television Network. Denis hosted her last show on May 23, 2008. In June 2008, Denis announced she would be hosting a new show,
The Marilyn Denis Show, on
CTV, which was scheduled to premiere in fall 2010. However, due to studio construction, the program premiered on January 10, 2011 on CTV. On April 13, 2023 she announced she would be ending the show on June 9, but would be continuing on as cohost on her CHUM radio morning show. On February 26, 2026, she announced her retirement from radio. ==Personal life==