The campaign will feature with a "Hair envy" gallery showing clients from salons with enviable hair.
Visitors can vote for the style that gives them hair envy and the winners will be featured in Marie Claire in November.
The "Hair envy" competition will be promoted on the Marie Claire website, in email newsletters, and with showcards in L'Oreal Professionnel salons nationwide.
Marie Claire's July issue also features a 24-page Hair Envy booklet, including features about hair colour and beauty looks, as well as listings for L'Oreal Professionnel colour consultation events and salons in UK and Ireland.
Alan Richardson, general manager, at L'Oreal Professionnel, said: "This is a unique approach in the hairdressing industry to support salons by promoting the benefits of in-salon colour.
"We hope to make salon colour easier for the consumer to understand, so they get the very best personalised service."
Richard Johnstone, Marie Claire's publishing director, added: "By creating a bespoke and fully integrated campaign that incorporated magazine, website, retail point of sale and below the line activity, we were able to meet strategic marketing needs of L'Oreal Professionnel and play to Marie Claire's unique brand strengths and resources."