Michelle Marsh went to the Crompton House CE School on Rochdale Road in High Crompton, where she took GCSEs in 1999. She grew up on Harewood Drive in Royton, where her company is still based.

She was interested in singing, acting and modeling from a young age, and initially appeared as an extra on soap operas such as Brookside from 1999 after leaving school. She later entered the TV sound-alike contest Stars in Their Eyes as Emma Buntonand competed in ITV's singing competition Popstars, before focusing on modeling. Before becoming a model, she worked as a care assistant at the Royley House Nursing Home in Royton. In June 2002, she won the Rochdale Observer Face of the Year competition, held at the local Liquid Rock Nightclub in Rochdale, which allowed her to have free modeling by DK Model Management in Sheffield.

In 2002 she became a Page Three girl for The Star newspaper, and in 2003 she started a successful modeling partnership with Lucy Pinder In 2003, she jointly hosted a Friday late-night programme on Oldham's The Revolution.

She has appeared in many magazines such as Loaded, Perfect 10, Nuts, Maxim, Zoo and Playboy. In the UK List of FHM 100 Sexiest Women poll 2005 Marsh was a new entry and finished 33rd overall. She finished in 47th in the 2006 poll. She has a tattoo of a religious cross with angel's wings bearing the word "Blessed" written across the middle on her lower back. It often appears in her current magazine shoots.

On 6 November 2006 Marsh released her first single "I Don't Do", which reached number five in the UK Indie Chart, but failed to appear in the Top 20 UK Singles Chart. It charted at 27 in the UK charts then dropped to 39 by its second week.

Marsh featured in the video to 4-4-2's single "Come On England", released ahead of UEFA Euro 2004. She has appeared on TV in The X Factor: Battle of the Stars, and Trust Me - I'm A Beauty Therapist. In late 2006 to early 2007 she co-hosted the second season of The Steam Room with Richard Alexander, on the ITV digital channel Men and Motors. The first season of The Steam Room was hosted by another famous Page 3 model, Jo Guest. In April 2007, Marsh made a guest appearance as a manager of a Boutique in ITV2's Reality TV show WAGs Boutique.