Katharine Mcphee is set to walk across New York's famous Brooklyn Bridge to raise funds for a children's charity.

The former American Idol star will lace up her shoes to join hundreds of participants as the grand marshal of the St. Jude Give Thanks Walk on 19 November (11).

The non-competitive five-kilometre (3.1-mile) trek begins in lower Manhattan and finishes across the East River in Brooklyn.

The event will kick off St. Jude Thanks and Giving campaign, which aims to raise awareness about childhood cancer and benefit the St. Jude Children's Research Hospital.