The Press Complaints Commission has extended its remit to cover publications which are available only online.
Until now, online versions of newspapers and magazines have come within the remit of the PCC but online-only publications have not.
The Press Standards Board of Finance (PressBoF) said the change will relate mainly to online magazines, where the publisher and editor must subscribe to the Editors' Code of Practice.
PressBoF chairman Guy Black said: "The internet is an increasingly important platform for publishers to reach consumers.
"While online versions of newspapers and magazines available in printed form come within the remit of the PCC, there is a gap to the extent that online-only publications do not.
"This decision is a logical development in self-regulation, recognising the moves in the magazine sector towards online-only titles, and underlines the effectiveness of our system".
PCC chairman Baroness Buscombe said: "We welcome the decision by the industry. The PCC needs this freedom to develop rapidly to meet the challenges and the opportunities presented by media convergence.
"One clear strength of the self-regulatory system is its flexibility to adapt to changing circumstances, while still providing a service that is free, fast, discreet and which involves the public in its decision-making."