The agency has been briefed to create a campaign to break in the New Year to support the gallery's new strategic positioning. This has been devised by the branding agency The Partners and focuses on the value of the permanent collection.
The initiative comes in the wake of increased activity from its London rivals Tate Britain and the National Portrait Gallery, both of which are seeking to raise their profiles.
This month, the Tate Gallery launched a press and outdoor campaign, developed by Fallon's strategic communications arm, Happen. It aims to change the public's perception of the museum.
Last year, The National Portrait Gallery unveiled a revamped identity, created by the design agency Rufus Leonard, to reflect its contemporary nature.
Dave Dye, the CDD creative director, said: "It's an honour to be asked to represent Raphael, Van Gogh and Caravaggio, to name but a few."
Media planning and buying for the National Gallery is handled by Total Media.
In 2004, the National Gallery was the most-visited museum or gallery in the UK, with almost five million visitors.