She joins a roll-call of inspiring public figures who use their status to promote and increase awareness of Scouting, which has 508,000 members in the UK.
The Dublin-born presenter, who fronted the Wainwright’s Walks series and completed his Coast to Coast Walk, celebrated her appointment by visiting the 13th Southall Scout Troop, where she met Scouts and leaders, and helped the troop to build survival shelters outside their meeting place.
After the meeting, Ms Bradbury said: “I always love seeing the enthusiasm of both the Scouts themselves and the Scout leaders and it has been inspirational to meet them.
“The 13th Southall is a wonderfully lively and energetic group which is so much fun to be around.”
The walking celebrity joins figures such as Ian Hislop, Chris Evans, Sainsbury’s chief executive Justin King, and London 2012 Olympics boss Lord Coe as ambassadors for the Scout movement, which was started by Robert Baden-Powell in 1907.
Scouting now has 28 million members in 216 countries across the globe. The movement, whose Chief Scout is adventurer Bear Grylls, is co-educational, welcoming both boys and girls.