Rupert Murdoch has elevated son Lachlan to the top of his multi-billion dollar family media empire after a seven year break.

Lachlan has been appointed non-executive co-chairman of both News Corp and 21st Century Fox.

The media mogul also gave his younger son James a bigger role as co-chief operating officer at 21st Century Fox, two years after he resigned as chairman of British broadcaster BSkyB following a parliamentary investigation into phone hacking.

Lachlan Murdoch, who has been serving as a director at News Corp and 21st Century Fox, will work closely with senior management to develop global strategies and guide the overall corporate agenda, the company said in a statement.

"Lachlan will help us lead News Corp forward as we expand our reach and invest in new technologies and markets around the world," Rupert Murdoch said in the statement.

Seven years ago, Lachlan Murdoch stepped back from the business his grandfather founded, quitting his role as deputy chief operating officer after clashing with his father and top executives.

Since then, he has focused on interests in Australia through his private investment company Illyria Pty Ltd, which owns various media assets.

Lachlan Murdoch also owns about 9% of Australia's third-ranked TV network, Ten Network Holdings, from which he stepped down as chairman today.