Mullin, who will become the charity’s first director of brand and marketing, will develop strategies to increase membership by broadening its appeal to younger people.
She will lead a restructured marketing department with new teams focusing on specific channels to market.
The charity, which looks after heritage properties, is looking to recruit a team of marketers including planners, online and direct marketing specialists, to populate the teams.
Fiona Reynolds, director-general of the National Trust, says that Mullin will help with its “ambitious plans to reach and deliver benefit to the whole nation”.
Mullin spent 11 years at Dyson with stints as communications director and international marketing director before becoming group marketing director in 2003. The National Trust job is her first since she left Dyson in 2009.