Twenty-six-year-old Bird becomes the title's youngest ever editor to lead the 13-strong editorial team.
He replaces Paul Rees, who left last month to head up sister Emap magazine Q as editor (PRWeek, 1 November).
Bird said that while Kerrang! enjoyed an all-time high in circulation figures - nearly 84,000 copies weekly according to ABC - he hopes to represent a wider range of rock music.
'We are a specialist magazine covering a genre of music that has so many different parts to it - we have got to represent that a bit better,' he said.
Features editor Dave Everley has also been promoted to deputy editor.
Ashley joined Kerrang! as reviews editor before working for the title on a freelance basis and as Kerrang!'s touring DJ, participating in the Kerrang! club tours and radio projects.