Long has more than 20 years' experience in the media industry.
In his new role, Long will oversee the strategic planning and development of the Cath Kidston and Heathrow accounts.
He joins Publicis Blueprint from his own company, Green Room Media, an independent sales and marketing business that he set up in 2009.
Prior to launching Green Room Media, Long was director of sales at Hachette Filipacchi, which in 2011, merged with the National Magazine Company and rebranded as Hearst Magazines UK.
Long has also worked at the National Magazine Company, where he was publisher of Good Housekeeping, and was also sales director at Diageo.