The 56-year-old 'Secret Diary of a Call Girl' actress was snapped up after becoming a viewers' favourite on BBC One's 'Strictly Come Dancing', according to The Sun.
Lunghi, the oldest female contestant on the show, is also the bookies' third favourite to win with odds of 6/1.
She is the latest in a long line of celebrities to appear in M&S ads including Myleene Klass, Lily Cole, Twiggy and Erin O'Connor.
It is not the first time that Lunghi has appeared in a high-profile ad campaign having starred in a long running series of Kenco coffee ads over nine years in the 1990s.
Lunghi recently said that she feels like she is "flying the flag for the older woman" but added that she wants to play women her own age and doesn't want to "go down the route of having plastic surgery".
M&S says it prides itself on catering to women of all ages, shapes and sizes. Earlier this month the retailer revealed that it is planning to launch a clothing line aimed at women aged 45 and older in response to a customer panel of women who claimed their needs were not being met by the store.
*M&S were evasive when asked to confirm the appointment, issuing a statement saying: "Marks & Spencer talk to lots of different people all the time with regards to new collections and campaigns."*