Pow replaced Michael Ellis in May as parliamentary under secretary of state for arts, heritage and tourism at the Department for Digital, Culture, Media and Sport.
Ellis served two months as minister of state at the Department for Transport before being appointed solicitor general by Johnson.
Pow’s responsibilities include tourism, heritage and cultural property, as well as the arts, museums, digital culture and public libraries.
She will also have oversight, under the guidance of sports minister Nigel Adams, for the horse-racing and gambling sectors, and lotteries.